Of Eusebius’ treatise on Easter,[91] dedicated to the Emperor, only a portion remains and this contains nothing either about Easter or its date. Constantine gratefully accepted the dedication in a letter which Eusebius, not without vanity, incorporated in his _Vita Constantini_ (4, 35). The Emperor’s encyclical,[92] communicating to the churches the conclusions concerning Easter arrived at by the Nicene Council, would have been more deserving of a place in the same work. 2. _The Connection of the Christian Festival with the Jewish_ The connection between the Christian and the Jewish feasts is both historical and ideal—historical because our Lord’s death happened on the 15th Nisan, the first day of the Jewish feast; ideal, because what took place had been prefigured in the Old Testament by types of which it was itself the antitype. The Jewish Passover was a repetition of what had taken place on the evening of the exodus from Egypt. On that occasion, the children of Israel had killed a lamb and marked their doorposts with its blood in order that the destroying angel might pass over their houses. Then, dressed for the journey, they had consumed the lamb at a ceremonial meal. This last meal of which the Israelites partook in Egypt on the eve of their departure, _i.e._ on the 14th Nisan, was of a religious character, and was, on this account, to be repeated every year on the same day, and at the same hour, as a memorial feast, at which each father of a family had to instruct his household in the signification of the rites they were performing.[93]