THE BIOLOGICAL SCIENCES AND MEDICINE. 801 



survived his younger contemporary by seven years, and takes pleasure 

 in acknowledging the French philosopher's appreciation of his great 

 discovery. 



In fact, Descartes accepted the doctrine of the circulation as pro- 

 pounded by " Hervseus, medecin d'Angleterre," and gave a full account 

 of it in his first work, the famous " Discours de la Methode," which 

 was published in 1637, only nine years after the exercitation "De 

 motu cordis " ; and, though differing from Harvey in some important 

 points (in which, it may be noted, in passing, Descartes was wrong and 

 Harvey right), he always speaks of him with great respect. And so 

 important does the subject seem to Descartes, that he returns to it in 

 the " Traite des Passions " and in the " Traite de I'Homme." 



It is easy to see that Harvey's work must have had a peculiar sig- 

 nificance for the subtile thinker, to whom we owe both the spiritualistic 

 and the materialistic philosophies of modern times. It was in the very 

 year of its publication, 1628, that Descartes withdrew into that life of 

 solitary investigation and meditation of which his philosophy was the 

 fruit. And, as the course of his speculations led him to establish an 

 absolute distinction of nature between the material and the mental 

 worlds, he was logically compelled to seek for the exjDlanation of the 

 phenomena of the material world within itself ; and, having allotted 

 the realm of thought to the soul, to see nothing but extension and mo- 

 tion in the rest of nature. Descartes uses " thought " as the equivalent 

 of our modern term " consciousness." Thought is the function of the 

 soul, and its only function. Our natural heat and all the movements 

 of the body, says he, do not depend on the soul. Death does not take 

 place from any fault of the soul, but only because some of the princi- 

 pal parts of the body become corrupted. The body of a living man 

 differs from that of a dead man in the same way as a watch or other 

 automaton (that is to say, a machine which moves of itself), when it is 

 wound up and has in itself the physical principle of the movements 

 which the mechanism is adapted to perform, differs from the same 

 watch or other machine when it is broken, and the physical principle 

 of its movement no longer exists. All the actions which are common 

 to us and the lower animals depend only on the conformation of our 

 organs and the course which the animal spirits take in the brain, the 

 nerves, and the muscles ; in the same way as the movement of a watch 

 is produced by nothing but the force of its spring and the figure of its 

 wheels and other parts. 



Descartes's " Treatise on Man " is a sketch of human physiology, in 

 which a bold attempt is made to explain all the phenomena of life, ex- 

 cept those of consciousness, by physical reasonings. To a mind turned 

 in this direction, Harvey's exposition of the heart and vessels as an 

 hydraulic mechanism must have been supremely welcome. 



Descartes was not a mere philosophical theorist, but a hard-working 

 dissector and experimenter, and he held the strongest opinion respect- 



VOL. XIX. 51 



