Pythagoras is one of the earliest thinkers credited with ideas about the origin of form in the biological production of offspring. It is said that he originated "spermism", the doctrine that fathers contribute the essential characteristics of their offspring while mothers contribute only a material substrate. Aristotle accepted and elaborated this idea, and his writings are the vector that transmitted it to later Europeans. Aristotle purported to analyse ontogeny in terms of the material, formal, efficient, and teleological causes (as they are usually named by later anglophone philosophy) – a view that, though more complex than some subsequent ones, is essentially more epigenetic than preformationist. Later, European physicians such as Galen, Realdo Colombo and Girolamo Fabrici would build upon Aristotle's theories, which were prevalent well into the 17th century.