physical system and beyond the powers of physics or chemistry to explain. This school of thought held that living matter was imbued with unique properties or animated by a special force—a philosophy called vitalism. To vitalists, biology’s task was to seek out the differences between living and dead things, not the commonalities. Such a view was not merely the territorial behavior or professional blinkeredness of biologists. Even eminent physicists such as James Clerk Maxwell, whose work revolutionized our understanding of electromagnetism and gases, believed that the chemistry of atoms, molecules, and elements could not explain living matter and that the laws of thermodynamics could not explain how bodies worked. And few biologists knew any mathematics, partly because it seemed irrelevant to their discipline and partly because of a feeling that to explain living forms in this way, to show that they fell within the orbit of sciences developed to explain dead matter, belittled them in a way that was almost immoral.
But Thompson was different. His familiarity with, and love of, the works of Aristotle, Pythagoras, and Plato had given him an expertise in mathematics, particularly geometry, far beyond that of most zoologists. He was a voracious polymath, willing to take inspiration anywhere. Classical, or renaissance, or enlightenment thinking was not obsolete; it was fundamental: “A fact discovered yesterday is balanced by the history of two thousand years,” he wrote. His intellectual roots lay in the time when educated people read and pondered everything, seeing no distinction between different branches of scholarship. And instead of seeing it as a debasement to bring mathematics into biology, he had the Greek belief in that discipline’s beauty and perfection.
Another thing that made Thompson an unusual biologist is that he thought his science should, following the example of physics, look for big answers and grand, overarching theories. Faced with the dazzling complexity of life, biology has traditionally been a science built of details and descriptions—from Linnaeus’s classification of species to the modern drive to sequence genomes. But Thompson belonged to another strand, which asks: Is there an underlying unity to nature? Can we discern patterns running through life’s diversity? Are there rules that might explain these patterns? And if so, are these rules the product of chance and history, or can we perceive them as the