The Lagoon: How Aristotle Invented Science

by Armand Marie Leroi

THAT MATTER FLOWS through living things, is transformed by them into the various uniform parts that they need to live and is distributed among those various uniform parts in a way constrained by economic laws – these are the elements of any metabolic theory. But any such theory must be underwritten by chemistry. Aristotle has a chemistry, but it is a poor one. It begins with the traditional four elements. Food and all its derivatives – the uniform parts – are compounds composed of these elements in particular proportions. Aristotle credits Empedocles with this idea, and Empedocles actually gives a formula for bone: E2W2AoF4, where E is earth, W is water, A is air and F is fire. Aristotle, by contrast, is very vague about the formulas of the uniform parts and generally speaks of them as being composed of just earth and water: hard uniform parts (bone, nails, hooves, horns, etc.) have lots of earth but little water; soft uniform parts (fat, semen, menstrual fluid) have little earth but lots of water; flesh is something in between. Aristotle suggests that such a formula is a step towards the definition of any uniform part. That makes sense since the recipe dictates its functional properties. All this is intuitive enough. But probe deeper, and difficulties appear. Aristotle berates Empedocles for merely thinking of the uniform parts as mixtures – agglomerated heaps of elements. They’re not, he says; they’re compounds – genuinely new substances. Very well, but how are such comp...