The Lagoon: How Aristotle Invented Science

by Armand Marie Leroi

ARISTOTLE DIVIDES THE soul among its functions. All living things have a ‘nutritive’ soul responsible for nourishment – trophē – and all that flows from it, but only animals (and humans) have a ‘sensitive’ soul that controls perception, appetite and locomotion. (He thinks that plants can neither sense their environment nor respond to it.) Humans also have a ‘rational’ soul. These sub-souls are components of a larger whole; sub-systems of the soul tout court. The nutritive soul is the first soul to appear in an animal’s development. Its powers are wide. It reigns over the acquisition, transformation and distribution of nutrition and hence the growth and maintenance of living things, their destruction by ageing and the perpetuation of their forms by reproduction. It holds them together and stops them from crumbling into dust. To put it more succinctly, when Aristotle talks about a creature’s nutritive soul, he’s talking about the structure and control of its metabolism. Metabolism: from the Greek metabolē – literally ‘transformation’. It’s a very Aristotelian word. A metabolism is the system by which an organism acquires matter from the world, transforms it into the stuff that it needs, and then redistributes to the places where it needs it. It is an open chemical system – which is what Schrödinger meant when he spoke of life feeding on negative entropy. Aristotle also perceived that living things were open systems: We must understand this [a growing uniform part] in terms o...