In Judaism, one of the most important and elaborate of religious festivals. Its celebration begins on the evening of the 14th of Nisan (first month of the religious calendar, corresponding to March–April) and lasts seven days in Israel, eight days in the Diaspora (although Reform Jews observe a seven-day period). Numerous theories have been advanced in explanation of its original significance, which has become obscured by the association it later acquired with the Exodus. In pre-Mosaic times it may have been a spring festival only, but in its present observance as a celebration of deliverance from the yoke of Egypt, that significance has been practically forgotten. In the ceremonial evening meal (called the Seder), which is conducted on the first evening in Israel and by Reform Jews, and on the first and second evenings by all other observant Jews in the Diaspora, various special dishes symbolizing the hardships of the Israelites during their bondage in Egypt are served; the narrative of the Exodus, the Haggadah, is recited; and praise is given for the deliverance. Only unleavened bread (matzoth) may be eaten throughout the period of the festival, in memory of the fact that the Jews, hastening from Egypt, had no time to leaven their bread. Jewish law also requires that special sets of cooking utensils and dishes, uncontaminated by use during the rest of the year, be used throughout the festival. In ancient Israel the paschal lamb (see Agnus Dei) was slaughtered on the eve of Passover, a practice retained today by the Samaritans.