A peculiarly Spanish one-act play produced mostly between the sixteenth and eighteenth centuries on the Feast of Corpus Christi* to elucidate the meaning of the Eucharist. It evolved from clergy bearing the host in a street procession, through floats depicting biblical scenes and choreography and drama, to written sacramental plays. From this emerged the secular and religious theater of the Spanish “golden age.” Competitions were held, with poets, actors, and prizes, leading to intercity rivalries and extravagance while the citizenry was entertained. As the cities' contribution to the feast, these plays tried to help the unknown be discovered through the known. Lope de Vega and José de Valdivielso brought this genre to maturity, while Calderón (1600-1681) raised the play to a near sacrament itself: “sermons set in verse, problems of Sacred Theology set in representable ideas. . . .” Rationalism brought the demise of autosacramentals; they were banned under Charles III (1765), but abroad have survived in some places.