"Let There Be Light," On October 22, 4004 B.C.

The Book of Genesis begins "In the beginning when God created the heavens and the earth." At some time thereafter "Then God said, "'Let there be light;' and there was light."  According to calculations made by James Ussher, Archbishop of Armagh, that first moment of creation took place at the onset of evening (6 p.m.) proceeding October 23, 4004 b.c.  These calculations were made by working backwards from the birth of Jesus in 4 b.c. (Ussher accounted for Dionysius' error in calculating the year of Jesus' birth) based upon the ages of the Patriarchs and the Kings of Israel as set forth in the Old Testament.

By Ussher's calculations, October 23 would have been a Sunday, the first day of the seven day week described in Genesis that would conclude on Saturday, the Sabbath day of rest.