The Nervous System: Circuits of Communication in the Human Body Medical Textbook on When Life Begins

Clark, J. ed., The Nervous System: Circuits of Communication in the Human Body, Torstar Books Inc., Toronto, 1985, page 99

“Each human begins life as a combination of two cells, a female ovum and a much smaller male sperm. This tiny unit, no bigger than a period on this page, contains all the information needed to enable it to grow into the complex …structure of the human body. The mother has only to provide nutrition and protection.”