23:14. Three times thou shalt keep a feast unto Me in the year.
1. It is curious to notice how, at a time considerably later than the origin of these public festivals, the exact day of their occurrence was made known. In these days of almanacs and of exact astronomical calculations, we can hardly appreciate the difficulties they encountered in finding the right time. The first appearance of the new moon was the starting-point. To ascertain this the Sanhedrin took the deposition of two impartial witnesses as to the time they had seen it. They next spread the intelligence through the country by means of beacons. A person with a bundle of brushwood or straw went to the top of Mount Olivet, where he kindled his torch and waved it back and forth till he was answered by fires of a similar nature from the surrounding hills. From these, in like manner, the intelligence was spread to others until the whole land was notified. After a time the Samaritans imitated the signs, thus making great confusion. This made it necessary to send messengers all over the country. These, however, did not go abroad at every new moon, but only seven times during the year. In this way the time for these three great feasts—Passover, Pentecost, and Tabernacles—as well as for other important occasions, was published to the people. See citation from Maimonides in Brown's Antiquities of the Jews, vol.1, p. 424.
2. These three festivals were preceded by a season of preparation, called peres, which lasted fifteen days. During this time each person was expected to meditate on the solemnity of the feast, and to undergo whatever legal purifications might be necessary. This is referred to in John 11:5555And the Jews' passover was nigh at hand: and many went out of the country up to Jerusalem before the passover, to purify themselves. (John 11:55). Roads, bridges, streets, and public water-tanks were repaired for the convenience of travelers.
3. All the males of Israel were expected to attend, excepting the aged, the infirm, and infants who could not walk alone. They were commanded to bring offerings with them.