446 THE ANIMAL FUNCTIONS. [ch. v. 



SECTION III. DO EACH OF THE DIVISIONS OF THE INTELLECT 



OCCUPY A SEPARATE PORTION OF THE BRAIN? 



It is our consciousness and a certain peculiar feeling which 

 convinces every one that he thinks with his brain. But since 

 the brain, as well as the cerebellum, is composed of many 

 parts, variously figured, it is probable, that nature, which 

 never works in vain, has destined those parts to various uses, 

 so that the various faculties of mind seem to require different 

 portions of the cerebrum and cerebellum for their production. 

 Since, however, the sensorium commune reflects the sensorial 

 impressions into motor by definite laws peculiar to itself, 

 and independently of consciousness, and since we have laid 

 down that the sensorium commune comprises the medulla ob- 

 longata, medulla spinalis, and the origin of all the nerves, it 

 follows that the cerebrum and cerebellum, together with their 

 connections, the sensorium commune excepted, constitute the 

 organs of the faculty of thought ; and as in some animals 

 these organs are entirely wanting, it is fair to conjecture that 

 the faculty of thought is also wanting, and that they exist 

 solely in virtue of the vis nervosa of the sensorium commune and 

 of the nerves with which they are endowed. Hitherto it has 

 not been possible to determine what portion of the cerebrum 

 or cerebellum are specially subservient to this or that faculty 

 of the mind. The conjectures by which eminent men^ have 

 attempted to determine these are extremely improbable, and 

 that department of physiology is as obscure now as ever it was ; 

 and we think with Haller that no light can be thrown upon it 

 in any other way than by a careful dissection of the brains of 

 fatuous persons, apoplectics, and such as have other disorders 

 of the understanding. There are indeed, many observations 

 extant bearing upon this point, but few have been rightly made, 

 and with many there is interwoven a preposterous judgment on 

 what has been observed. As hitherto there has been so much 

 reason to lament the dearth of judiciously-made observations, 

 I hope more ingenious men may be incited to note, as occasion 



* The sentiments of the Arabians may be seen in § iii of chap, i; and in § vi, the 

 opinion of WilUs, Lancisi, De la Peyronie, and Mayer. 



