The penis does not obey the order of its master, who tries to erect or shrink it at will. Instead, the penis erects freely while its master is asleep…The penis must be said to have its own mind, by any stretch of the imagination. -Leonard Da Vinci (1504)
The human body is an extraordinary and complicated machine. This machine requires perfect interaction between its billions of cells to accomplish the myriad tasks it performs every day of our lives. Each of these tasks, or biological functions, is a miracle. The fact that our body performs the even greater miracle of effortlessly performing these physical and mental functions that make us human, without our assistance, is beyond mortal comprehension. Two of these physiological miracles are the male reproductive and urinary systems. These two systems share one organ, the penis, which serves as the literal tip of the spear for the final step in their joint biological processes.