Hans Driesch

Born in 1867, he trained as a zoologist and became widely known for embryology experiments that challenged strictly mechanical accounts of development. By separating early sea urchin cells and showing that each could develop into a whole larva, he helped shape later thinking about regulation and development in living organisms.

Over time, his scientific work led him toward philosophy. He became a leading advocate of neo-vitalism, arguing that living beings could not be fully explained by physics and chemistry alone, and he used the term entelechy for the organizing principle he believed guided life.

He died in 1941, but his name remains important both in the history of biology and in debates about vitalism, organism, and the limits of mechanistic explanation. Even readers who disagree with his conclusions often find his experiments and questions historically significant.