igS FROM FISH TO PHILOSOPHER 



the sun, moon, and stars, and he considered man and 

 animals to be, basically, very complicated machines/ 

 Aristotle had sought to explain the differences between 

 inanimate matter and plants by means of a Vegetative 

 soul,' between plants and animals by means of a 'sen- 

 sitive soul,' and between animals and man by means of 

 a 'rational soul.' Descartes rejected Aristotle's Vegetative' 

 and 'sensitive' souls, seeing in plants only the mechanical 

 product of a developing seed, and in animals only curi- 

 ously contrived machines that have neither consciousness 

 nor feeling but 'act naturally and by springs, like a 

 watch.' 'The greatest of all prejudices we have retained 

 from our infancy,' he wrote, 'is that of beHeving that the 

 beasts think.' Their 'life' is merely the beat of the heart, 

 their 'feeling' merely the autoreaction of an organ, as 

 when a plant moves to or away from the sun. 



But, so it seemed to Descartes, man transcended ani- 

 mals by virtue of the fact that he was a thinking, rational 

 being, and to explain this difference he retained in man's 

 behaff Aristotle's 'rational soul,' coupling it to the me- 

 chanical body through the pineal gland, which was con- 

 veniently located close to the brain and for which there 

 was no other demonstrated function. 



Here, in the pineal gland, mind meets matter; here, 

 receiving passively the data of the senses, it cogitates 

 upon them; and here, in vohtion, it bends the body to 

 its 'will.' 



This Cartesian dichotomy between 'matter' and 'mind' 

 lingers on not only in common parlance but in philoso- 

 phy, giving rise to frequent discussions of the 'mind- 

 brain problem* or the 'mind-body problem.' Some critical 

 thinkers continue to adhere to duahsm, holding to the 

 behef in something called 'mind' which is other than 

 matter, but the majority of workers in the biological sci- 

 ences reject the belief in the existence of disembodied 

 mind and see in 'mind' a mode or property of matter, 

 so that psychical processes are wholly dependent on 

 physical and chemical events in the nervous system. This 



