CHAPTER Xin 



CONSCIOUSNESS 



The illusion of unchanging personality is probably com- 

 mon to all normal mammals with advanced brains. This 

 illusion, as it appears to man, has long enjoyed the sup- 

 port of errors engendered by prescientific speculation, 

 and notably by the dualism of Rene Descartes (1596- 

 1650), the most eminent philosopher of seventeenth- 

 century France. Descartes was initially interested in 

 mathematics, to which subject he contributed analytical 

 geometry and the famihar co-ordinates known by his 

 name. Then mathematics led him into astronomy and 

 to speculations about the origin and nature of the imi- 

 verse. Here he rejected the 'spirits' and 'genii,' to which 

 even Kepler had assigned the movements of the heavenly 

 bodies, in favor of an atomistic interpretation, and he 

 bequeathed to physics the laws, first, that so long as a 

 body is unaffected by extraneous forces it continues in 

 the same state of motion or rest; and second, that simple 

 or elementary motion is always in a straight line. He 

 sought a natural explanation for gravity, heat, magnet- 

 ism, and light; and, his own momentum carrying him 

 in a straight line, he conceived that all chemistry, physi- 

 ology, and biology could be explained in mechanical 

 terms. 



Descartes was as much concerned with expelling 'spir- 

 its' and 'genii' out of physiological phenomena as out of 



