“There are then three rules given in the Sacred Writings, whereby the time of keeping Easter has been appointed for us and may in no wise be changed by any authority of man; two whereof are divinely established in the law of Moses; the third is added in the Gospel by reason of the Passion and Resurrection of our Lord. For the law enjoined, that the Passover should be kept in the first month of the year, and the third week of that month, that is, from the fifteenth day to the one-and-twentieth. It is added, by Apostolic institution, from the Gospel, that we are to wait for the Lord’s day in that third week, and to keep the beginning of the Paschal season on the same. Which threefold rule whosoever shall rightly observe, will never err in fixing the Paschal feast. But if you desire to be more plainly and fully informed in all these particulars, it is written in Exodus, where the people of Israel, being about to be delivered out of Egypt, are commanded to keep the first Passover,(953) that the Lord spake unto Moses and Aaron, saying, ‘This month shall be unto you the beginning of months; it shall be the first month of the year to you. Speak ye unto all the congregation of Israel, saying, In the tenth day of this month they shall take to them every man a lamb, according to the house of their fathers, a lamb for an house.’ And a little after,(954) ‘And ye shall keep it up until the fourteenth day of the same month; and the whole assembly of the congregation of Israel shall kill it in the evening.’ By which words it most plainly appears, that in the Paschal observance, though mention is made of the fourteenth day, yet it is not commanded that the Passover be kept on that day; but on the evening of the fourteenth day, that is, when the fifteenth moon, which is the beginning of the third week, appears in the sky, it is commanded that the lamb be killed; and that it was the night of the fifteenth moon, when the Egyptians were smitten and Israel was redeemed from long captivity. He says,(955) ‘Seven days shall ye eat unleavened bread.’ By which words all the third week of that same first month is appointed to be a solemn feast. But lest we should think that those same seven days were to be reckoned from the fourteenth to the twentieth, He forthwith adds,(956) ‘Even the first day ye shall put away leaven out of your houses; for whosoever eateth leavened bread, from the first day until the seventh day, that soul shall be cut off from Israel;’ and so on, till he says,(957) ‘For in this selfsame day I will bring your army out of the land of Egypt.’