By the mosaic law, every mother, after giving birth to a son, remained unclean for seven days, in the first instance, and then, for thirty-three days longer, was excluded from participation in public worship. After the birth of a daughter the period of ceremonial uncleanness was twice as long. Thus the whole period lasted for forty or eighty days, and at its conclusion the woman had to bring a yearling lamb for a holocaust and a pigeon for a sin-offering. In case of poverty, two young pigeons or turtle-doves sufficed as an offering (Lev. xii. 2-8). According to the narrative in the Gospels, Mary, after the birth of Jesus, fulfilled the commands of this law and brought the prescribed offering to the Temple on the fortieth day, on which occasion the meeting with Simeon and Anna took place (St Luke ii. 22 _et seqq._). Our Blessed Lady and her divine Son, in the first place, and, secondarily, Simeon and Anna are the actors in this scene, and it would have been strange had this event not been commemorated very early among the Church’s festivals. The first reference to such a commemoration belongs to the last decades of the fourth century and comes from Jerusalem. It is contained in the diary of the so-called Silvia. The day was ushered in by a solemn procession, followed by a sermon on St Luke ii. 22 _seqq._, and a Mass. It had as yet no special name, but was known merely as the fortieth day after the Epiphany. This goes to prove that at that time the Epiphany was regarded in Jerusalem as the day of the Lord’s birth, and it follows indirectly from the expressions used (_hic_) that the festival was not yet known in the Pilgrim’s home.[391] It seems probable that the festival was first of all observed in Jerusalem from whence it spread through out the whole Church. The person by whom, and the time when it was first introduced into Constantinople and the Byzantine empire, are known to us. A plague having caused frightful mortality, the Emperor Justinian, as soon as it had passed away, ordered the Purification to be observed for the first time in 542.[392] The contradictory evidence in Georgius Hamartolus and Nicephorus[393] that it was the Emperor Justin, Justinian’s predecessor, who introduced the festival and ordered it to be observed throughout the world, seems due simply to a confusion between the two emperors. In any case the spread of the feast throughout a wider area dates from this time.