We are composed of about ten trillion cells. The retina of the human eye alone contains three million cells, each connected to the brain by an individual wire in the cable of the optic nerve. Our brain contains 100 billion cells, linked by 100 trillion synaptic connections. Yet, we are part of the evolutionary process, descended from single-cell organisms that lived 3.5 billion years ago.
— Daniel C. Matt, God & The Big Bang