The influence of Judaism upon Christian symbolism as early as the 2nd and 3rd centuries A.D., is apparent both in painting and in sculpture, the most frequent motives being those that occur in the Mishnah as formulas for prayer on fast-days. The prayer beginning with the words "Mi she-'anah," which was included in the selihah at an early date, was adopted in the Christian ritual as the litany "Libera domine." This litany was figuratively used in a certain sequence as a symbol, for the sacrifice of Isaac was regarded as a symbol of the crucifixion of Jesus, since the early religions, and the act of sacrifice emblemized the death on the cross.