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Today鈥檚 biologists think like Aristotle (Image: Prisma/UIG/Getty Images)

The ancient Greek philosopher deserves our homage, and Armand Marie Leroi delivers it in his edifying and excellent book

EVERY generation of biologist must rediscover Aristotle for itself, to paraphrase Armand Leroi in a BBC documentary, Aristotle鈥檚 Lagoon.

Four years on, Leroi, a biologist at Imperial College London, has written a book with nearly the same name. The full fruits of the author鈥檚 decade of immersion in Aristotle, it represents both Leroi鈥檚 personal discovery of the ancient Greek and a quest to recover his science for biologists today.

Once a highway, this path has been trodden by only a few life scientists in four generations. And in taking it, the author retraces Aristotle鈥檚 footsteps to Kalloni lagoon on the island of Lesbos, where the philosopher studied nature, providing charming vignettes from his visits there.

There is a serious purpose, too. Aware that scientists tend to distort past thinkers by imposing present conceptions and values on them, Leroi argues that today鈥檚 biologists can think like Aristotle because he forged their basic concepts, and because nature shows us the same phenomena. But to best understand Aristotle, a biologist must see what he saw in Lesbos.

鈥淭oday鈥檚 biologists can think like Aristotle because he forged their basic concepts鈥�

The Lagoon is an intellectual homage 鈥� an admiring, deeply researched and considered reconstruction of Aristotle鈥檚 thinking about living things. The effort to get inside his head seems driven by a heartfelt sympathy, a sense of wonder about life on Earth shared across 2300 years, and by the modern scientist鈥檚 urge to give credit where credit is due.

And for Leroi, Aristotle deserves credit for nothing less than inventing biology 鈥� perhaps even science. Earlier philosophers, like his teacher Plato, deduced stories about the fundamental causes of natural phenomena from first principles. But physicians in the empirical tradition, to which Aristotle was exposed by his physician father, learned how to predict the course of disease from observation. Aristotle was arguably the first to attempt an evidence-based natural philosophy (or 鈥渟cience鈥�), melding empiricism with logic.

The book is structured with major sections corresponding to topic areas in Aristotle鈥檚 work, such as taxonomy, nutrition, or cosmology, each broken into half a dozen short chapters, often containing Leroi鈥檚 Lesbos experiences to make the natural phenomena accessible and intriguing. For example, we learn about the vigorous argument he observed among taverna patrons over whether sardelles and papalinas are really the same fish (they look similar but taste different, and live in different waters). This example of the classification problem nicely introduces Leroi鈥檚 discussion of Aristotle鈥檚 taxonomic system.

The prose is so lively, the thinking so lucid, and the use of such devices so artful, one might not notice it all adds up to a 500-page systematic analysis of a massive, dry, sometime jumbled philosophical corpus from a profoundly alien society. That many readers will come away entertained, and with even a slightly better understanding of Aristotle would be a major literary feat even if the book did not offer significant original contributions.

But it does. Take Leroi鈥檚 account of Aristotle鈥檚 concept of soul, psyche. It is well thought through, closely argued on textual evidence, and innovative. As my wonderful teacher, classicist Arthur Adkins, said, psyche was 鈥渇or Greeks only the difference between a dead rabbit and a live rabbit鈥�. In other words, to explain psyche is to explain life.

Leroi shows that Aristotle was no vitalist, in the sense that he required nothing more than ordinary matter and its properties to explain life. He understands that for Aristotle the soul was its form (eidos, which can also mean species), the order of a creature鈥檚 material 鈥� a pattern of activity constituting its life.

Organisation as life is a view remarkably close to modern biology: for Leroi, biology is all about mapping the body鈥檚 regular material transformations. I am sympathetic to his effort to credit Aristotle with something very like modern biological insights, and indeed, I find Leroi鈥檚 arguments that Aristotle invented the concepts of metabolic networks and feedback control plausible.

Leroi offers another innovation in finding a 鈥渄ual-inheritance鈥� theory in Aristotle鈥檚 writing, resolving the conundrum of form (eidos again) coming only from the father and the undeniable phenomenon that children resemble both parents. Thus, for Aristotle the movements of the generative fluids of female and male can, without major self-contradiction, transmit details of form (like Socrates鈥檚 snub nose) less significant than those defining the species, imparted by the father.

Elsewhere in Leroi鈥檚 discussion of reproduction, we read: 鈥淲hat is the immediate source of the design that we see in living things? It is the information that they inherit from their parents.鈥� Or, to paraphrase the BBC documentary again, Aristotle taught that material self-assembles into organisms only with the help of information.

Here Leroi goes too far. Despite acknowledging the danger of anachronism, he is actually likening the Aristotelian concept of eidos to modern biology鈥檚 notion of genetic information. Biology鈥檚 concept of information is less than a century old, deriving from computer science. Psyche, the realisation of a creature鈥檚 eidos, was an activity, more like an oscillation than a formula or code.

Furthermore, the Greeks did not have the problem vitalism and materialism both answer. Our premise that ordinary matter must be utterly passive stems from Reformation Christianity. Without this expectation, the difference between dead and alive is not as radical as we perceive. For ancient Greeks, all matter was dynamic, living matter only more so.

From this perspective we can see why Aristotle accepted spontaneous generation without anxiety: putrefying matter, already seething with change, could accidentally fall into self-perpetuating patterns of activity and thus spin off organisms 鈥搈aggots in corpses or oysters in mud. Insufficiently attuned to the animism (or more accurately, hylozoism) of the Greeks, Leroi unfairly scolds Aristotle for inconsistency with his own metaphysics and his mature theory of reproduction.

Such quibbles are not meant to detract from this marvellous book. Leroi鈥檚 Aristotle is a fit hero for the biological century, and The Lagoon is a work as important to a historian and philosopher of science as it is informative to a biologist and entertaining to the general reader. As compelling as Stephen Jay Gould鈥檚 best work, it will long outlast most nature writing of recent years.

This article appeared in print under the headline 鈥淪cience鈥檚 true begetter?鈥�

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