God’s Machines: Descartes and Nature

As a young man, the not-yet-famous philosopher René Descartes lived for a while in a very famous place: Saint-Germain-en-Laye, 20 km outside Paris, where French kings had been building magnificent residences since the 12th century. By the 1600s the palatial châteaux were not even the main attraction. King Henry IV had commissioned two renowned Italian engineers, the Francini brothers, to embellish his gardens with lifelike moving automata and intricate hydraulic amusements, all sophisticated enough to rival those of the grand dukes of Tuscany.

These ‘frolicsome engines’, as they were known, were all the rage across Europe. The essayist Michel de Montaigne spent the summer of 1581 admiring one Italian grotto where he saw ‘not only music and harmony made by the movement of the water, but also a movement of several statues and doors with various actions, caused by the water; several animals that plunge in to drink; and things like that’. Unsuspecting visitors even found that ‘all the seats squirt water on your buttocks’ (although that trick got old after a while). Soon enough, the residents of Saint-Germain could also marvel at lifelike mechanical wonders of their own. In his work on physics and physiology, the Treatise on Man, Descartes describes a grotto where spectators: 

cannot enter without stepping on certain tiles which are arranged in such a way that, for example, if they approach a Diana bathing they will cause her to hide in the reeds, and if they move forward to pursue her they will cause a Neptune to advance and threaten them with his trident; or if they go in another direction they will cause a sea monster to emerge and spew water in their faces; or other such things depending on the whim of the engineers who constructed them.

By the time the Treatise on Man was published in 1662, 12 years after Descartes’ death in 1650, he was viewed as a philosophical revolutionary and one of the principal founders of the ‘new science’, along with figures such as Galileo Galilei, Francis Bacon, and Thomas Hobbes. In 1633 Galileo had been arrested and imprisoned for following Copernican astronomy in placing the sun at the centre of the universe. This was the reason for the posthumous publication of Descartes’ treatise: he simply could not risk being seen to hold the same view, since it went against the received understanding of holy scripture, which placed the Earth at the centre of everything. Nevertheless, he fully subscribed to the new scientific understanding of the world, in which our solar system is just one among many. He shelved his manuscript and, instead, published a different, more autobiographical kind of work: the Discourse on Method, in which he recounted his own search for a ‘method for conducting one’s reason well and attaining truth in the sciences’. There, Descartes aimed to illustrate the discipline of cultivating a wakeful, attentive, considerate mind: a mind trained to separate reason and unreason, sensitive to its own biases and propensity for self-deception and doubt.

This short text makes him, today, one of the most quoted philosophers in the world. It contains his catchphrase, ‘je pense, donc je suis’, also known as ‘cogito, ergo sum’, or ‘I think, therefore I am’. Descartes founded his new philosophy on the reasoning mind. Doubting is a kind of thinking, so the argument goes; so if I am doubting, I cannot doubt that I am thinking, even if nothing else about the world or my body is true. That basic dualistic insight (my mind versus the world) gave him the kind of certainty he was looking for in the sciences: a foundational insight that could be built upon.

But the Discourse is also famous (and infamous) for other assertions, too. Animals, wrote Descartes, can be considered ‘comme une machine’: not just like a machine, but as a machine. Considering the bones, muscles, nerves, arteries, veins, and all the other parts that are in the body of every animal, he concluded that they all worked together just like a complete hydraulic system, or a large mechanical clock. Descartes wanted to understand all such processes. If we study the world, he said, then, ‘knowing the power and action of fire, water, air, stars, the heavens, and all the other bodies that are around us as distinctly as we know the different trades of our craftsmen, we could put them to all the uses for which they are suitable, and thus make ourselves as it were the masters and possessors of nature’.

Very often, these combined statements, all consistent with the new science, have conjured up awful images of animals as unfeeling entities, and the entire natural world as a resource that humans can exploit at will. Many of Descartes’ readers have understood his text in this way. An internet search for his views currently produces a generative-AI summary along the following lines: ‘Descartes’s philosophy, particularly his ideas about the human-nature relationship, has been criticized for contributing to an ecological crisis due to his anthropocentric worldview, metaphysical dualism, and mechanistic view of nature.’

Thinking back to the marvellously lively machines that Descartes grew up with, though, and harnessing the idea of the ‘different trades of our craftsmen’, can help us understand things differently. Craft brings in a sense of careful skill and scale: an artisanal use of natural resources, rather than a plundering. And we should remember that, for Descartes, the entire universe can be conceived as an unimaginably vast mechanism. Within it, both animal and human bodies function in exactly the same way. These living body-machines, which comprise instinct and sensation, are so extraordinarily complex, so ‘astounding’, that they can be manufactured only by God. God’s machines will always be ‘incomparably more complex’, wrote Descartes to his friend, the mathematician Marin Mersenne, than anything that humans could come up with.

Early 17th-century machines were intricate, impressive, responsive, and lively in equal measure. Even so, for Descartes just as for the other proponents of mechanistic science, the natural, living world will always surpass even the most sophisticated contraptions. In its subtle matter and its infinite wonder, it always retains an element of the unknowable. In this way, we can read 17th-century philosophy today not just for its statements about mechanism and mastery, but for the form of environmental awareness it brings with it. As their elements collide, rotate, and interact, the automata of the world encourage a respect for natural processes. After all, as Descartes says, the whole of his philosophy is also ‘like a tree’, a growing, changing thing: metaphysics as its roots, physics as its trunk, but its branches spreading out towards ‘the ultimate degree of wisdom’.

Emma Gilby is Professor of Early Modern French Literature and Thought at the University of Cambridge, and the author of Descartes and the Non-Human (Cambridge University Press Elements, 2025).