There are a few simple facts to remember about the exodus of the Hebrews from Egypt that is described in the second book of the Torah. They are these:
- The first plague must have taken place at the very start of the inundation, as only then did the Nile take on a reddish-brown hue, the rains of Ethiopia having washed its red earth downstream into Egypt.
- The next nine plagues occur throughout the coming months into the winter season. The winter crops have been ripening and the Bible, when the wrath of God supposedly brings down hail to destroy the crops, gives a telling clue that it is only sometime in late January or early February because only certain of the crops were ripening and the others had not yet matured.
- The legend had it, according to the Jewish historian, Flavius Josephus, that the exodus took place in the Egyptian month of Pharmouti, the month of threshing, ideally corresponding to April/May. After that month the harvest is done. Pharmouti must also correspond to the Hebrew month of Nisan [by retroactive reckoning] and this only happens during limited periods in Egyptian history. In some years, the 15th of Nisan, the day of the departure, will fall within other months in the Egyptian civil calendar. For example, in 1359 BCE, a year in the reign of Amenhotep III, the 15th of Nisan would fall on Julian 21st of April—but this would amount to 27 Pakhons by the civil calendar.
- Nearly all of the ancient historians were convinced that an exodus occurred during the sway of the 18th Dynasty, yet not all agreed as to the reigning pharaoh. But, giving another example, April 3, 1482 BCE, probably a year in the reign of Thutmose III, amounts to 8 Pharmouti and 15 Nisan 2279. I do not know the year in which the Biblical exodus was supposed to have occurred. Perhaps no one did by the time the Book of Exodus was written. However, it is obvious, even from the way the plagues are described, that it had to be in what we call the spring season. Therefore, the Jewish calendar was devised as a lunar-solar one, so that the month of Nisan would always fall in the spring. However, since the Egyptian civil calendar was a lunar one without leap years, this was not the fate of the month of Pharmouti, which could fall within any of the three naturally-occuring seasons of Egypt but was in what we view as the spring only at limited times.