294 LAY SERMONS, ESSAYS, AND REVIEWS. [xiv. 



According to Descartes, then, all the functions which are 

 common to man and animals are performed by the body as a 

 mere mechanism, and he looks upon consciousness as the peculiar 

 distinction of the &quot; chose pensante,&quot; of the &quot; rational soul,&quot; which 

 in man (and in man only, in Descartes opinion) is superadded 

 to the body. This rational soul he conceived to be lodged in the 

 pineal gland, as in a sort of central office ; and, here, by the 

 intermediation of the animal spirits, it became aware of what 

 was going on in the body, or influenced the operations of the 

 body. Modern physiologists do not ascribe so exalted a function 

 to the little pineal gland, but, in a vague sort of way, they adopt 

 Descartes principle, and suppose that the soul is lodged in the 

 cortical part of the brain at least this is commonly regarded as 

 the seat and instrument of consciousness. 



Descartes has clearly stated what he conceived to be the 

 difference between spirit and matter. Matter is substance 

 which has extension, but does not think; spirit is substance 

 which thinks, but has no extension. It is very hard to form a 

 definite notion of what this phraseology means, when it is taken 

 in connection with the location of the soul in the pineal gland ; 

 and I can only represent it to myself as signifying that the soul 

 is a mathematical point, having place but not extension, within 

 the limits of the pineal gland. Not only has it place, but it 

 must exert force ; for, according to the hypothesis, it is competent, 

 when it wills, to change the course of the animal spirits, which 

 consist of matter in motion. Thus the soul becomes a centre of 

 force. But, at the same time, the distinction between spirit and 

 matter vanishes ; inasmuch as matter, according to a tenable 

 hypothesis, may be nothing but a multitude of centres of force. 

 The case is worse if we adopt the modern vague notion that 

 consciousness is seated in the grey matter of the cerebrum, 

 generally ; for, as the grey matter has extension, that which is 

 lodged in it must also have extension. And thus we are led, 

 in another way, to lose spirit in matter. 



In truth, Descartes physiology, like the modern physiology of 

 which it anticipates the spirit, leads straight to Materialism, so 



