CALENDAR. Calendars are devised as a trustworthy means for recording history and determining dates in advance for social, civic, and religious anniversaries, and for economic planning. Comparatively little is known of the calendar of the early Israelites from the patriarchs to the Exile, but a critical study of the biblical records and archaeological discoveries is rewarding.

During the Bible period, time was reckoned solely on astronomical observations. The early Chaldean and Egyptian astrologers became quite learned in the movements of astronomical bodies. Their discoveries, as well as those of other Near Eastern neighbors, made their impact on the Jewish calendar. From earliest times the sun and moon were determinants of periods: days, months, and years.

I. Days in the biblical record of time begin with the account of creation. Various reckonings and measurements were derived from these early records. While the Babylonian day began at sunrise, the Bible reckoned the twenty-four-hour span from sunset to sunset (Deut.23.11), probably taking its clue from the repeated phrase of Gen.1.5, Gen.1.8, et al. Neh.4.21 suggests that the end of one day and the beginning of the next was actually marked by the appearance of the stars.

Days of the week were not named but were designated by ordinal numbers. The term “sabbath” was not the name of the seventh day but a sacred designation.

Early Hebrews divided the night into three watches: “the morning watch” (Exod.14.24); “the middle watch” (Judg.7.19); and “at the beginning of the watches” (Lam.2.19 rsv). The Romans divided the night into four watches, from which Jesus drew an analogy in his eschatological warning of unpredictable time: “ the evening, or at midnight, or when the rooster crows, or at dawn” (Mark.13.35).

II. Weeks constituted special and significant units of time for the “chosen people.” The seven-day week is of Semitic origin, but reckoned from various reference points. The Babylonians and Assyrians bound their weeks to the lunar cycle, corresponding with the four phases of the moon, and began anew with each new moon. The biblical week had its origin in the seven-day creation account and ran consecutively in a free-week system irrespective of lunar or solar cycles. This was out of the high esteem held for the Sabbath. The Egyptian week had ten days.

Astronomical bodies were divinely ordained in creation to be time markers. Days and years were measured by the sun; months by the moon; and cycles by sun, moon, and stars. The week alone was not controlled by celestial bodies, but originated by divine command for man’s economic, physical, and spiritual welfare.

Though God placed special emphasis on the seventh day at the time of creation (Gen.2.2-Gen.2.3), the records are silent as to its observance during the long interlude between then and Moses’ day. If the people of the pre-Flood era or of the patriarchal period observed a “sabbath,” there are no biblical records of it. However, since sabbath observance was kept alive in tradition until recorded in Genesis, it is a reasonable conjecture that it was preserved in practice also. Anyway, it was either revived or given special emphasis by Moses. The first recorded instance of the observance of “a day of rest, a holy Sabbath to the Lord” (Exod.16.23) was when the Israelites were gathering manna in the wilderness. Subsequently, the Sabbath became the most holy, as well as the most frequent, of all the sacred days observed by the Jews.

III. Month, in effect, is a synonym for moon. Apparently all ancient peoples worshiped the moon. They also measured time by it, because of its regular cycles. The Arabic word for moon means “the measurer,” and the Egyptian moon god Thoth was the god of measure. Even apostate Jews at times worshiped the moon along with other heavenly bodies (2Kgs.23.5; Jer.8.2).

“Moon” was synonymous with “month” in common parlance in Moses’ day (Exod.19.1). Later, when religious responsibility was vested in the Sanhedrin, three of their number, including the chief, were entrusted as watchmen to report the first appearance of the new moon. A declaration of the beginning of a new month was then quickly dispatched over the country by fire signals, and later by messengers. The Jewish scholar Hillel (c. 60 b.c.-a.d. 20) probably introduced the constant calendar.

The early Israelites designated their months by names that they borrowed from the Canaanites or Phoenicians. These names had seasonal connotations as implied in the four that have survived in the early biblical records. Abib (Exod.13.4; Deut.16.1), corresonding to Nisan in the later calendar, means “month of the ripening ears.” Ziv (1Kgs.6.1), corresponding to Iyyar, means “month of flowers.” Ethanim (1Kgs.8.2), corresponding to Tishri, means “month of perennial streams.” Bul (1Kgs.6.38), corresponding to Marchesvan, means “rain or showers,” being the first month in the rainy season.

About the end of the kingdom period the calendar was reformed, replacing the old names of the months with ordinal numerals and changing the beginning of the year from fall to spring. This is illustrated in 1 Kings (1Kgs.6.1; 1Kgs.8.2), where the writer explicitly correlated the numeral month with older names, as “the month of Ziv, the second month.” On the other hand the writer of Haggai (1Kgs.1.1; 1Kgs.2.1, 1Kgs.2.10), about 520 b.c., at the time of the rebuilding of the temple, uses the numeral designation of months without any explanatory references. Yet Zechariah, a contemporary work, relates the numeral month to the Babylonian names, which came into popular use after the Exile: “the eleventh month, the month of Shebat” (Zech.1.7; see also Zech.7.1).

The postexilic names of months were, as confirmed by the Talmud, adopted from the Babylonian calendar but not used for civil and historical purposes. These, like the early Canaanite names, had their origin close to nature, as is seen from their derivations. Nisan—“move,” “start,” is the first month of the ecclesiastical year as well as of the vernal equinox. Iyyar—“to be bright,” “flower.” Sivan—“appoint,” “mark.” Tammuz—name of an ancient Akkadian god identified with vegetation. Ab—“hostile” heat, “bulrushes” growing. Elul—“to shout for joy” at vintage. Tishri—“begin” civil year, “dedicate” to the sun-god by Babylonians, and to which the Jews might have associated the Creation and the Day of Judgment. Marchesvan—“drop,” “rainy season.” Kislev—derivation uncertain. Tebeth—“to sink,” “dip.” Shebat—also uncertain. Adar—“to be dark.”

The Gezer Calendar, dated in the tenth century b.c., gives an interesting glimpse into the agricultural life in Palestine at that early date. This archaeological find by Macalister is a limestone plaque bearing a Hebrew inscription enumerating farm operations for eight months, mentioning sowing, flax harvest, barley harvest, and vine pruning.

IV. Years. The OT calendar contained two concurrent years: the sacred year, beginning in the spring with the month Nisan, and the civil year, beginning in the fall with Tishri. The sacred year was instituted by Moses following the Exodus and consists of twelve or thirteen lunar months of 29 1/2 days each. The civil year claims a more remote antiquity, reckoning from the Creation, which traditionally took place in autumn (3760 b.c.). It came into popular use in the third century of the Christian era. That this order of the year was kept by the ancient Hebrews is supported by the Mosaic command “Celebrate the Feast of Ingathering at the end of the year, when you gather in your crops from the field” (Exod.23.16).

The Babylonians and Egyptians devised the intercalary month in order to reconcile the lunar and solar years. The Jewish leap years in their Metonic cycle of nineteen years were fixed, adding an intercalary month to the third, sixth, ninth, eleventh, fourteenth, seventeenth, and nineteenth years. If, on the sixteenth of the month Nisan, the sun had not reached the vernal equinox, the month was declared to be the second Adar and the following one Nisan.

In 46 b.c., a great advance over contemporary calendars was made by Julius Caesar, whose calendar year contained 365 1/4 days. It had a discrepancy of eleven minutes in excess of the solar year, and so was superseded by the Gregorian Calendar in a.d. 1582, which was adopted in England in 1752. It has the infinitesimal error of gaining one day in 325 years.

Josephus (Antiq. 1.3.3) said that Moses ordered that the year of holy days and religious festivals begin with Nisan, the month in which the Exodus transpired, but that he retained the old order of year for buying and selling and secular affairs. This observation has been confirmed by critical study and subsequent Jewish custom of keeping both a sacred and a civil year.

Feasts and fasts were intricately woven into the lunar-solar sacred year. Three great historic feasts were instituted by Moses: “the Feast of Unleavened Bread,” “the Feast of Harvest,” and “the Feast of Ingathering” (Exod.23.14-Exod.23.16), corresponding roughly to Passover, Pentecost, and Thanksgiving. There were also numerous minor feasts.

Beginning in the month Nisan or Abib (Neh.2.1; Exod.23.15), the sacred holidays of feasts and fasts came in the following order: On the fourteenth of Nisan, the first month, the Passover (Exod.12.18-Exod.12.19; Exod.13.3-Exod.13.10) was observed in preparation for the following week’s festival and in eating the paschal supper (see Matt.26.17-Matt.26.29). The fifteenth to twenty-first was the Feast of Unleavened Bread (Lev.23.6), which included, on the fifteenth, a Sabbath, a day of holy convocation; on the sixteenth, Omer, or presenting the first sheaves of harvest; and on the twenty-first, another holy convocation. This is also the month of latter or spring rains when the Jordan was in flood (Josh.3.15).

The Christian Easter, fulfilling the Passover, is reckoned on solar-lunar cycles, coming on the first full moon on or after the vernal equinox (March 21).

The name of the second month, Iyyar, known formerly as Ziv (1Kgs.6.1, 1Kgs.6.27), does not occur in the Bible, as is also true with Tammuz, Ab, and Marchesvan. The Jews fasted on the tenth in commemoration of the death of Elijah; the fourteenth was the Second or Little Passover for those who could not keep the regular one (Num.9.10-Num.9.11); and on the sixteenth was a fast for the death of Samuel.

Winter holy days were few, though one of significance is mentioned in John.10.22-John.10.23: “Then came the Feast of Dedication at Jerusalem. It was winter, and Jesus was in the temple area....” Dedication of the temple was instituted by Judas Maccabeus in 164 b.c. This feast was held on the twenty-fifth of Kislev (Zech.7.1), which was followed by the tenth month, Tebeth (Esth.2.16), and the eleventh month, Shebat (Zech.1.7).

Besides the one divinely ordained fast, the Day of Atonement, there were minor fasts, some temporary (Ezra.9.5; Neh.1.4) and some annual. One fast in memory of the destruction of Jerusalem by Nebuchadnezzar (2Kgs.25.1-2Kgs.25.7), instituted after the Exile, was observed on the ninth of Ab. Another, the fast of Esther, was observed on the thirteenth of Adar and was followed the next two days by the Feast of Purim.

V. Cycles. From God’s hallowing of the seventh day there arose a special sacredness in relation to the number seven. Religious convocations and festivals were highly regarded on the seventh day, seventh week, seventh month, seventh year, and seven times seven years.

Hence, the epitome of the sabbatical feasts, of which the perennial ones have been mentioned, may thus appear. The sabbath of seven days; Pentecost, at the end of seven weeks after Passover; and the Feast of Trumpets, introducing the sacred seventh month, were all “appointed assemblies” (mo’adhim) of the Lord.

The sabbatical year was one of solemn rest for landlords, slaves, beasts of burden, and land, and of freedom for Hebrew slaves. Only what grew of itself on the farm and vineyard was to be gathered and consumed (Exod.23.10-Exod.23.11; Lev.25.3-Lev.25.7). The sabbatical and jubilee years were synchronized with the civil or agricultural year, beginning in autumn.

The Jubilee, every fiftieth year, following “seven weeks of years,” was a hallowed year whose observance included family reunions, canceled mortgages, and the return of lands to their original owners (Lev.25.8-Lev.25.17).

VI. Eras in the Bible calendar constitute the whole span of time from the creation of the world to the consummation of the ages. Great events are terminal markers. These mountain peaks of time, in chronological sequence, are Creation, Flood, Abraham, Exodus, Exile, and Birth of Jesus. Consequently, the eras may be designated Ante-Diluvian, Post-Diluvian, Patriarchal, Israelite, Judean, and Christian. (Cf. Matt.1.2-Matt.1.17; Luke.3.23-Luke.3.37).

Astronomically, the phenomenal star that guided the Magi divided human history. It is the pivotal point from which all history is dated, terminating the old order and initiating the new. It stands as the signal reference point of all time, the preeminent red-letter date in the Bible calendar. In the Jewish Calendar it separates the history “Before the Common Era” (b.c.e.) from that of the “Common Era” (C.E.). In the Christian calendar it separates all “Before Christ” (b.c.) from that in Anno Domini (a.d.), “The year of our Lord.”——GBF

Primitive man measured his calendar by the cycle of recurring natural phenomena which he observed, such as the alteration of day and night and the phases of the moon. The calendar in use in NT times was the Julian, based on the Roman republican calendar. By 46 b.c. the republican calendar had grown out of step with the seasons to the extent of three months, and the seasons were no longer in proper relationship with the calendar months. Julius Caesar instituted a four-year cycle, the first three having 365 days and the fourth 366, the additional day being placed in February. The fourth years were known as bissextile years. The modern term “leap year” is derived from the Old Norse hlaupar. In the Julian calendar each year was eleven minutes fifteen seconds too long, a fact which was significant only over a long period. After several delays the new Gregorian calendar was promulgated by Gregory XIII in 1582. The leap year rules were altered to deal with the fault in the Julian calendar, and ten days were omitted from 1582 to balance the accumulated error. The calendar is now correct to within one day in 20,000 years. The Gregorian calendar, now used for civil purposes throughout the world, was not generally adopted immediately. Great Britain did not adopt it until 1752, and the Russians did not do so until the rise of the Soviet government in 1917. The Orthodox Church has not adopted it, with the result that its year is now thirteen days behind the Gregorian year. The Gregorian calendar restored New Year's Day to 1 January. Formerly it was 25 March, the supposed anniversary of the Annunciation. The date of Easter is calculated in reference to the epact (the age of the moon at the beginning of the year), and the rules laid down by the Council of Nicea are largely adopted. Other Christian festivals have fixed dates.

Limestone tablet inscribed with a school text of an agricultural calendar; from Gezer, about the 10th century. Copyright (c) ''O.I.U.C.''

CALENDAR, a system of measuring time by reference to recurring phenomena or to computed intervals.


Origins and development


The calendar is one of the oldest forms of applied science; its purpose is not merely to keep records, but also to predict developments. In a community whose livelihood depends on seasonal opportunities (e.g., for agriculture, or hunting, where the game moves with the seasons), one must know the right time for action.

Religion added incentives for prediction, in the general belief that sacrifices were required to insure success in agriculture or hunting; and success called for thanksgiving as well as joy. In true religion as in false, observances must be scheduled to enable the community to unite in fellowship, or consecration, or desire. It fell to the priests to maintain the calendar, a task certainly beyond the ability of the unskilled. The Samaritan claim was typical (Bowman, VetTest 15 [1965], 120ff.); calculations depended partly on the correct text of instructions, partly on an expertise which only the priests could have.


As trade increased, a calendar became an essential basis for contracts. Within the more advanced communities, the functions of administration (esp. fiscal and judicial) needed a calendar to fix periods and systematize records. In government and trade, wider horizons and more sophisticated organization called for more compatible, standardized calendars.

An imperial power might impose its own calendar or adopt that of a conquered civilization. The Pers. conquerors of Babylon first adopted the Babylonian calendar, then imposed it throughout their later empire (Bickerman, p. 24). The Romans found no system in their Gr. dominions which commanded any wide acceptance; but their own calendar was so erratic that, eventually, Julius Caesar carried out a thorough reform. He did this without disturbing the festivals from their places within each month, or removing nominal control from the priests; as Segal says (JSS 6, 74ff.), a calendar which breaks completely with ancient traditions is not likely to survive for long. Caesar’s reconciliation of tradition and science gave Europe a stable solar calendar based on computation, and resolved the tension between conservative and systematizing tendencies.

While there is no absolute need to use a solar year, there are good practical reasons for matching everyday reckoning to the climatic cycle. The history of the calendar is largely concerned with the attempt to reconcile observational and climatic factors; the former proved more complex and subtle than was at first suspected.

Natural conditions


Climatic changes (cyclic variations in the weather) control the growth and ripening of the earth’s produce: (1) rainfall promotes growth directly, and causes rivers to appear or rise, sometimes in countries which do not themselves receive appreciable rain; (2) insolation, varying with the sun’s altitude, affects the heat of the earth and hence of the atmosphere; this in turn affects the prevailing winds and the rainfall. All climatic conditions, the seasons, and the growth of crops, depend ultimately on the sun and on the fact that the earth’s axis is not perpendicular to the ecliptic.

In many parts of the world, the heating of the land during the day produces an onshore wind, if meteorological conditions are otherwise stable.



Daily change in the sun’s meridian altitude corresponds to the climatic cycle. It is possible, but it requires skill and apparatus, to determine the solstices and equinoxes to within a day. The solar or tropic year is approximately 365.24 mean solar days. Since the earth’s orbit is slightly elliptic, the fall equinox comes about 186 days after the spring (vernal) equinox.


The moon’s phases are readily observed, but less easy to determine precisely, except for the phasis; even here, since the moon moves half a degree eastward (relative to the sun) in each hour, the crescent might be seen in Pal. on a night when it had not appeared in Babylonia; cloud or haze may also hinder observation. The altitude of the crescent varies, partly because of the varying inclination of the ecliptic to the horizon, partly because the moon may be up to five degrees N or S of the sun. The moon’s synodic period (lunation) is about 29.53 days.


The stars are the most accurate indicators of time; being so far from the earth, they appeared fixed until astronomers could make precise measurements. From the point of view of the man-in-the-field, their unvarying pattern goes through an annual cycle corresponding to the sun’s movement against the stellar backcloth. A constellation appears farther to the W each evening, until it no longer appears before sunset. Soon afterwards, it becomes visible in the E before dawn (heliacal rising) and rises earlier each night until it is again visible at sunset.

From very early times the stellar cycle was associated with the seasons, but only after many centuries did the annual shift become apparent. Precision causes (a) a shift of the solstices and equinoxes with reference to the Zodiac; (b) a shift of the equatorial plane in relation to the ecliptic, so that stars which once rose or culminated at the same time no longer do so.


Biblical terms.



Shabua’ (seven-day period) occurs in the OT, mainly in connection with the Feast of Weeks and in the prophecies of Daniel. In the NT, “sabbath” is used as a dating reference and as a period (Luke 6:1). See below, par. V (E.).


Yeraḥ (Akkad.) from yāreaḥ, the moon (as a visible object) is used (a) for a lunation; (b) for a specific month; (c) in counting months. Hōḏesh, from hāḏāsh, new, meaning the crescent or the day of its appearance, hence the reference for dating within a month; found throughout the OT as a common synonym for yeraḥ. See New Moon.



For yāmīm, days, see above (1.h). Shānāh, turning or change, the great cycle which governs all human activity. Connected with it are: T’qūp̱āh, circuit (Ps 19:6), end of period (1 Sam 1:20), of the year (Exod 34:22, at the fall harvest; cf. 2 Chron 24:23); in Judaism, the quarter-days, each of which was the “new year” for a different purpose. Teshūḇāh, return, i.e. of the campaigning season (2 Sam 11:1; 1 Kings 20:22, 26; 2 Chron 36:10).


Celestial sphere: the imaginary background on which the movements of the heavenly bodies, as seen from the earth, can be traced. Position is defined by degrees of declination from the celestial equator toward the N or S celestial poles (corresponding to latitude), and by right ascension in hours eastward from the vernal equinox, which is the prime reference.

Conjunction: the position of two bodies being in the same direction (longitude) from the earth.

Ecliptic: the apparent path of the sun on the celestial sphere. The plane of the ecliptic is the fundamental reference for the solar system.

Epact (annual): the difference in time between the lunar and solar years (about eleven days).

Epagomenal Days: days added in the calendar to compensate the epact or other such difference; distinct from intercalary days as being part of the calendar and not an interruption of it.

Equinox: point on the celestial sphere where the ecliptic intersects the equator. At the vernal equinox the sun passes from N to S declination.

Golden Number: the remainder from dividing a year date (nodetitle) by 19, plus 1. This defines the moon’s phases (and all dependent dates) for that year, in accordance with the Metonic cycle.

Heliacal rising: the annual date when a star is seen to rise immediately before dawn. Though not a very precise observation, it was the best way of determining a point in the solar year before accurately calibrated instruments were available.

Intercalation: interruption of calendar sequence to insert an extra unit, ad hoc or regularly.

Longitude: measurement of degrees eastward from the vernal equinox in the ecliptic plane.

Lunation: period between two conjunctions of the moon and the sun (also synodic month).

Metonic Cycle: period of nineteen years, after which the moon’s phases repeat their celestial positions; discovered by the Gr. astronomer Meton in the 5th cent. b.c. The inaccuracy is only one day in twelve cycles (228 years).

Phase (lunar): the appearance of the moon at a given point in its orbit round the earth.

Phasis: the first appearance of the new moon.

Precession: a steady oscillation of the earth’s axis in relation to the ecliptic, in a period of 25,800 years. With reference to the fixed stars, the equinoxes move around the ecliptic, being now 70o from their position in 3000 b.c. The Taurus period denotes the time before about 2500 b.c., when the vernal equinox was in Taurus.

Solstice: time when the sun reaches its maximum declination; position of the sun at this time.

Year: a solar or tropic year is the time in which the sun returns to the vernal equinox. A lunar year is twelve lunations.

Zodiac: the ecliptic divided into twelve zones of 30o for computational purposes, named in Babylonian times after the constellations in the zones.

Names of months.





















































Calendar systems

Hebrew calendars and their derivatives.

The agricultural year ended at the harvest of grapes and fruit (Exod 23:16; 34:22; cf. Lev 25:8f.). The seasons had climatic or agricultural names; the Gezer Calendar attempted to correlate these with a system of lunar months, but did not give names to the months. “Canaanite” names, used in official records (1 Kings 6:1, 37f.; 8:2), apparently required interpretation later. The term ḥōḍesh hā'āḅīḅ, month of green ears, is used only in Exodus and Deuteronomy in connection with the Passover (cf. Exod 9:31; Lev 2:14).

Numbering of the months, from the passover month (Exod 12:2), is applied in the Pentateuch and in the few cases arising in the histories (Josh 4:19; 1 Kings 12:32f.; 2 Kings 25; and Esther, where Babylonian names are used but rarely alone; cf. Ezra 6:15; Neh 1:1; 2:1 only). Numbers are used by Jeremiah, Ezekiel, Haggai, and (without “month”) Zechariah. Numbering was important for merchants and administrators, and need not have arisen from Babylonian influence, as Morgenstern (HUCA I) and others assume. For the general population, the festivals marked the annual cycle. These had to follow lunar and solar (agricultural) indications; intercalation must have been practiced, but nothing is said about it in the OT; regulations were not yet possible.

Orthodox Jewish.

The Jews had a lunisolar calendar on the Babylonian model, intercalating a second Adar and eventually standardizing seven intercalations in nineteen years, though the Mishnaic rules leave the final decision in the hands of the Sanhedrin. According to the tractate Rosh hashshanah, great attention was paid to the observation of the new moon; but it was laid down that there could not be more than seven, nor fewer than five, thirty-day months in any year.


a. The Book of Jubilees refers to a calendar of much interest, which abandoned the lunar month for one of thirty days. The year was divided into quarters, each of three months and an epagomenal day (i.e., thirteen weeks), so that all dates fell always on the same day of the week, and festivals never clashed with the sabbath. At the same time, it kept clear of Hel. systems which, like the Babylonian, were tending to a nineteen-year cycle.

The discovery of Jubilees texts at Qumran has revived debate as to whether this calendar could ever have been used in a community. It would have meant abandoning the solar year; no scheme of intercalation seems to avoid compromising its fundamental principles.

b. Qumran. Discrepancy between the orthodox and “covenanter” calendars was a major ground of contention, illustrated by the story that the Wicked Priest affronted the Teacher of Righteousness on what the Teacher, but evidently not the Priest, held to be the Day of Atonement. Qumran seems to have agreed with Jubilees at least in regarding the week as primary, and the calendar as a matter of revelation. Reference to the moon is disputed (Talmon, Scripta Hierosoly mitana 4 [1958]; Bowman PEQ 1959). Kutsch (Vet Test 11) considers intercalation only of weeks, but Vogt (Biblica 39) believes that it was used to reconcile Essene and solar years.

c. Samaritan. The Tolidah shows points of contact with Jubilees; but certain prayers show that the month could begin on the sabbath. Baumgarten (Vet Test 16) regards the calendar as basically lunar.

d. Elephantine. The syncretistic community here, prob. from Northern Israel, used Pers. (i.e., Babylonian) and Egyp. dating, but observed at least the Passover according to Jewish tradition.

Theories of development.

The Pentateuch does not describe a calendar; it assumes a lunisolar basis. The historical books only give information sporadically; little is known of the observance of festivals under the Judges, or during the ebb and flow of religion under the kings. A series of articles by J. Morgenstern in HUCA demonstrates the scope available to speculation. His theory of an original “Canaanite” solar calendar, replaced in the 6th cent. by one of Babylonian type, was later withdrawn (JBL 83, Vet Test 5) in favor of the pentecontad theory of J. and H. Lewy; both ignore the evidence of the Gezer Calendar and the OT references to the new moon. Derivation of a pentecontad (fifty-day period) from a module of seven, squared and “rounded up,” is suspect both in assumptions and logic (fifty is not “round” unless a base other than seven is already used). Segal (Vet Test 7) points out that natural events rather than computed intervals must dominate the calendar of an agricultural people.

In HUCA XXI, Morgenstern redefined Solomon’s calendar as lunisolar and “Tyrian” (376f.); after many vicissitudes, the pentecontad was revived by the deuteronomists (433), although they numbered the months ordinally (436). Many inconsistencies reveal the unsound methodology of these theories.

Gentile calendars.


Calendars were developed by each of the principal cities; that of Nippur, adopted by Sargon I, became standard. The text enbu bel arḥim (Nineveh, 7th cent.) is the oldest full account, but some “menologies” of propitious and unlucky days date from the second millennium. The earliest calendars were prob. lunisolar; according to Langdon, intercalation was used to keep the barley harvest in Adar. A cycle of seven intercalations in nineteen years was in use by the 4th cent.; but a 7th cent. prism provides for beginning a year at the new moon nearest the vernal equinox. By the 2nd cent. conjunction and phasis were found by computation.


Little is known beyond the names of certain months (Ethanim, Bul as in 1 Kings 6 and 8; Lezib, Hiyyar, see Koffmahn, Biblisch Zeitschrift 10 [1966], 217). Worship of the heavenly bodies figured largely in Phoen. religion, but it does not appear that they worshiped the sun more than the moon, nor can their knowledge of the Zodiac imply that they used a standardized month.


The Egyp. year began at the Nile flood, and was divided into four seasons of three months. The heliacal rising of Sirius marked this year; but the official calendar (twelve months of thirty days, and five epagomenal) was allowed to creep forward, rotating through the year in what became known as the “Sothic” (Sirius) cycle.


State calendars were the responsibility of the magistrates; varying use was made of the schemes proposed by astronomers for establishing a regular cycle of intercalation. The Macedonian calendar, known chiefly from its use in Egypt by the Ptolemies, had months of twenty-nine days and thirty, alternately; intercalation was irregular. By 117 b.c., the Egyp. calendar was readopted, using Macedonian month names. The Seleucids used the Babylonian calendar with Macedonian names.


Many features of our calendar are Rom. in origin; the January new year (adopted 53 b.c.), the short February, and the names of the months. The Romans neither observed a lunar month, nor did they master intercalation. Caesar introduced a solar year based on a value of 365 1/4 days, which Hipparchus had already shown to be slightly too large; but as the cumulative error is only a day in a cent., it continues to serve, with the Gregorian adjustment.

Some problems

The new year.

Both spring and fall new years are recognized in the Pentateuch (e.g., Exod 12:2; 34:22), and implied in the historical books. Some have maintained that the spring new year came to Judah with the Babylonians (so Finegan, ss. 67f.; it is a non sequitur that the later use of Babylonian names with the numbers indicates a Babylonian origin of the number-system). Morgenstern sees agricultural grounds for both fall and spring—in his original and later theories respectively.

Date of the Passover.


In the Pentateuch, the Passover is firmly dated on the fourteenth day of the first month; but the lack of any historical reference between Joshua (Josh 5) and Hezekiah (2 Chron 30) has been taken to support the hypothesis that the relevant legislation was postexilic; there are grounds for holding that Hezekiah and Josiah gave a new slant to a familiar observance, making it a pilgrimage rather than a local festival. See J. Wilcoxen, Biblical Research 8 (1963), for a review.

(Matt 26:17; Mark 14:12; Luke 22:7) was eaten as a passover; John 18:28 indicates that the Jews had not yet eaten it. Discoveries at Qumran, while not directly relevant, open the possibility of differences of practice within Judaism, particularly when a feast fell on the eve of a sabbath.

Fall observances.

The Day of Atonement (Exod 30:10; Lev 16) is not mentioned in Kings, nor, more surprisingly, in Nehemiah. A later origin has therefore been supposed, but this conclusion is not inevitable, in view of the general ignorance of the law even in Ezra’s time.

Morgenstern (HUCA I, 22f.) argues from Exodus 23:16; 34:22; Deuteronomy 31:10; that the harvest festival formerly preceded New Year’s Day; but this rests on too strict an interpretation. It would be more natural to hold such a festival at full moon.

The northern kingdom.

Jeroboam I instituted a feast at Bethel on the fifteenth of the eighth month. This may well reflect the later harvest in the N; and if he, in fact, altered the calendar by one lunar month, this may partly explain the second month Passover of Hezekiah when he was canvassing support in Israel (Talmon, Vet Test 8).

The Sabbath.

Shabbāt (pause, rest) was prob. not derived from sheḇa’ (seven). A cognate Akkad. sapattu denoted the fifteenth of a month, though it may have been used earlier for the epagomenal period (Lewy, HUCA XVII, 78ff.); the 7th, 14th and 28th, though esp. marked, were not restdays in our sense; cf. Langdon p. 83. See Sabbath.


B. Landsberger, Der Kult. Kalendar (1915); P. Nilsson, Primitive Time Reckoning (1920); J. Morgenstern, HUCA I (1924), 13-78; G. Dalman, Arbeit u. Sitte I (1927); S. Langdon, Babylonian Menologies (1933); J. and H. Lewy, HUCA 17 (1941), 1-152; J. Morgenstern, HUCA 20 (1947), 1-36, 21 (1948), 365-496; R. Parker, Calendars of Ancient Egypt (1950); A. Jaubert, Vet Test 3 (1953), 250-264; S. Horn and L. Wood, JNES 13 (1954), 1-20; R. Parker, JNES 14 (1955), 271ff.; J. Morgenstern, Vet Test 5 (1955), 35-76; R. North, Biblica 36 (1955), 82-201; J. Obermann, JBL 75 (1956), 285-297; O. Neugebauer, Exact Sciences in Antiquity2 (1957); A. Jaubert, Vet Test 7 (1957), 35-61; J. Segal, ibid., 250-307; E. Vogt, Biblica 39 (1958), 72-77; S. Talmon, Vet Test 8 (1958), 48-74; E. Auerbach, ibid., 337-343, Vet Test 9 (1959), 113-121; J. Bowman, PEQ (1959), 23-37; E. Kutsch, Vet Test 11 (1961), 39-47; F. North, ibid., 446-448; J. Segal, JSS 6 (1961), 74-94; B. Rahtjen, PEQ (1961), 70-72; S. Talmon, JAOS 83 (1963), 177-187; J. Morgenstern, JBL 83 (1964), 109-18; W. Hartner, JNES 24 (1965), 1-16; J. Baumgarten, Vet Test 16 (1966), 277-286; H. Stroes, ibid., 460-475; E. Bickerman, Chronology of the Ancient World (1968).

International Standard Bible Encyclopedia (1915)

The Hebrew or Jewish calendar had three stages of development: the preexilic, or Biblical; the postexilic, or Talmudic; and the post-Talmudic. The first rested on observation merely, the second on observation coupled with calculation, and the third on calculation only. In the first period the priests determined the beginning of each month by the appearance of the new moon and the recurrence of the prescribed feasts from the vernal and autumnal equinoxes. Thus, the month Abib (’abhibh), the first month of the year according to the Levitical law, in which the Passover was to be celebrated, was determined by observation (Ex 12:2; De 16). After the exile more accurate methods of determining the months and seasons came into vogue, and calculation was employed to supplement and correct observations and the calendar was regulated according to the Babylonian system, as is evidenced by the names of the months which are derived from it. In later times the calendar was fixed by mathematical methods (see the article "Calendar" in the Jewish Encyclopedia). The difficulty of ascertaining the first day of the new moon by observation, in the early period, led to the celebration of two days, as seems to be indicated in 1Sa 20:27. We have only four names of months belonging to the pre-exilic period, and they are Phoenician. Of these Abib (’abhibh) was the first month, as already indicated, and it corresponded to Nis (nican) in the later calendar. It was the month in which the Exodus occurred and the month of the Passover (Ex 13:4; 23:15; 34:18; De 16:1).

The year (shanah) originally began in the autumn, as appears from Ex 23:16 and Ex 34:22, where it is stated that the feast of Ingathering should be at the end of the year; the Sabbatic year began, also, in the 7th month of the calendar year (Le 25:8-10), indicating that this had been the beginning of the year. This seems to have been a reckoning for civil purposes, while the year beginning with Nican was for ritual and sacred purposes. This resulted from the fact that the great feast of the Passover occurred in this month and the other feasts were regulated by this, as we see from such passages as Ex 23:14-16 and De 16:1-17. Josephus (Ant., I, iii, 3) says: "Moses appointed that Nican, which is the same with Xanthicus, should be the first month of their festivals, because he brought them out of Egypt in that month; so that this month began the year as to all solemnities they observed to the honor of God, although he preserved the original order of the months as to selling and buying and other ordinary affairs." A similar custom is still followed in Turkey, where the Mohammedan year is observed for feasts, the pilgrimage to Mecca and other sacred purposes, while the civil year begins in March O. S.

The year was composed of 12 or 13 months according as to whether it was ordinary or leap year. Intercalation is not mentioned in Scripture, but it was employed to make the lunar correspond approximately to the solar year, a month being added whenever the discrepancy of the seasons rendered it necessary. This was regulated by the priests, who had to see that the feasts were duly observed at the proper season. The intercalary month was added after the month of ’Adhar and was called the second ’Adhar (sheni, wa-’adhar, "and Adar"), and, as already indicated, was added about once in 3 years. More exactly, 4 years out of every 11 were leap years of 13 months (Jewish Encyclopedia, article "Calendar"), this being derived from the Babylonian calendar. If, on the 16th of the month Nican, the sun had not reached the vernal equinox, that month was declared to be the second ’Adhar and the following one Nican. This method, of course, was not exact and about the 4th century of our era the mathematical method was adopted. The number of days in each month was fixed, seven having 30 days, and the rest 29. When the intercalary month was added, the first ’Adhar had 30 and the second 29 days.