From a verbal root ephoraom already in Homer conveying general vision and specific supervision, there emerged the designation for a specific office of overseer, ephoros. By the time of Herodotus the five annual eponymous ephors at Sparta were understood to constitute its government. General usage is also known, since it is but a rarer, alternate Greek derivation with little essential distinction from episkopos. Hence, by the fifth century a.d. Philostorgius can make the equation, apply a verbal form to the bishop's rule, and identify by nominal derivative the diocese of Tyre. “Ephor” takes on a restricted use after the tenth century, when it is applied to the lay overseer of Byzantine monastic property.