Biblical scholars place the story of Joseph and the famine, recounted in Genesis 41 and 47, in the Second Intermediate Period (1674-1553 B.C.). Joseph, endowed with the ability to interpret dreams, advised Pharaoh that his two dreams of seven lean ears of corn devouring seven good ears and seven lean cows arising from the Nile eating the seven fat cows which preceded them meant that Egypt would enjoy seven good years of harvests followed by seven bad years.
To prevent this disaster and possible destruction of Egypt, Pharaoh appointed Joseph to supervise the collection of a fifth of the grain output in the seven plentiful years and store it for subsequent distribution and sale in the seven lean years. Sure enough, Pharaoh’s dream came true, but the storehouses of grain saved Egyptians and their neighbors from starvation.
From this episode, Joseph established as law the principle that a fifth of the produce grown in the land of Egypt belongs to Pharaoh. This principle was reestablished in July 2005 when a new code slashed the top personal rate from 32 to 20 percent (with two lower rates of 10 and 15 percent) and set the corporate rate at 20 percent.