Descartes was prepared to extend his guess to the whole set of natural processes defining the human being (save for rational thought and action under control of the conscious will). In the early 1630s he composed a Treatise on Man ( Traité de l’homme) , which he suppressed on learning of Galileo’s condemnation in 1633. It appeared only posthumously, in 1664, when it was published along with another unfinished work, this one from 1647/8, The Description of the Human Body ( La Description du Corps Humaine) . The latter is sometimes titled “On the Formation of the Fetus,” though this is misleading as this is only part, albeit an important part, of what the work covers. The Treatise begins deliberately with the supposition that God has built a statue which is a “machine made from earth,” with a heart, a brain, and so on, but a contrivance which in detail works much like a clock, only in more complicated ways. The complex mechanisms are assumed to be able to approximate those of a human, but as it is imagined as a machine we will not be tempted to attribute its motions to the various mysterious powers, vegetative and sensitive souls, and so on, as did Aristotle and the Scholastics. Descartes’ program aimed to show that all but rational and deliberately willed and self-conscious behavior could, in principle, at least, be explained as material processes operating according to mechanistic laws. He therefore elaborates “how possibly” such a machine might work. He describes how a “man of earth” analogous to clocks and to the automata, powered by water and doing various things, constructed by engineers for the gardens of the rich, but incredibly more complex, might be constructed by God and how it might work. The mechanisms envisioned by Descartes for this “man machine” in the Treatise are quite complex, although in comparison to what we now know of these mechanisms, they are simplistic and crude. The Description is a more curious work, dealing with the development of the human being from sperm through fetus to grown adult person. It consists mainly of assertions and coarse sketches of the mechanisms supposed to be involved. It was still a “how possibly” explanation, but it certainly was less persuasive than other parts of Descartes’ sketches of a non-Galenic, non-Aristotelian mechanistic vision of the human body.
In late 1646, Queen Christina of Sweden initiated a correspondence with Descartes through a French diplomat and friend of Descartes’ named Chanut. Christina pressed Descartes on moral issues and a discussion of the absolute good. This correspondence eventually led to an invitation for Descartes to join the Queen’s court in Stockholm in February 1649. Although he had his reservations about going, Descartes finally accepted Christina’s invitation in July of that year. He arrived in Sweden in September 1649 where he was asked to rise at 5:00am to meet the Queen to discuss philosophy, contrary to his usual habit, developed at La Fleche, of sleeping in late,. His decision to go to Sweden, however, was ill-fated, for Descartes caught pneumonia and died on February 11, 1650.