Then Jesus was led up by the Spirit into the wilderness to be tempted by the devil. And after He had fasted forty days and forty nights, He then became hungry. (Matthew 4:1,2)
Alice C. Linsley
Numbers are an interesting and useful device in tracking the tribal and ethnic origins of a document. For example, the Chinese avoid using the number four, which they regard as a bad omen, yet four is a sacred number to the Plains Indians of North America and is used in their ceremonies. The number four, representing the directional poles, is an essential part of preparing the gound for the Oglala's Vision Quest.
In the Bible we are able to track the origin of some narratives using number symbolism. The Bible comes to us from the ruler-priests of the anceint world whose number symbolism can be classified into Proto-Saharan and Babylonian traditions. In the ancient Habiru/Hebrew tradition the number forty appears often, largely as a reference to the Nile, but the number forty is less significant in the Babylonian tradition.
For example, the story of Noah's flood speaks of rain for "forty days and forty nights", but in the Book of Daniel, which is rich in number symbolism, the number forty doesn't appear even once. The Book of Daniel comes from ancient Babylon. And all the evidence of Genesis points to Noah's flood taking place in the region of Mega-Chad in west central Africa.
The number forty in the western Afro-Asiatic tradition relates to the periodic forty day flooding of the Nile when people living near the banks had to leave their homes. The second forty relates to the additonal forty days they had to wait for the waters to receed before they could return to their homes. The Coptic monks speak of the forty days, always aware of the connection to the periodic flooding of the Nile which dispersed nutrient-rich silt over the farm land. Read here about a Coptic monk's understanding of Genesis.
Noah was a Proto-Saharan ruler in the region of Lake Chad at a time when water systems connected the Nile and Lake Chad. The context of the phrase "the forty days and forty nights" of rain is Nilotic, not Meopotasmian. Likewise, Israel's forty years of wandering in the wilderness indicates that this narrative reflects a Nilotic context, rather than a Mesopotamian context.
Related reading: Number Symbolism in the Bible; Discrepancies are Evidence of Authenticity