ON THE FUNCTIONS OF THE BRAIN 65 



have an historic value for us, in the proof that this great philosopher 

 recognized two things in the brain : first, a physiological mechanism ; 

 and then, above and beyond that, the thinking faculty of the soul. 

 These ideas are nearly the same with those that afterward prevailed 

 among many philosophers and some naturalists ; the brain, in which 

 the most important functions of the nervous system are performed, 

 was for them not the real organ of thought, but simply the substratum 

 of intelligence. Indeed, the objection was often enough expressed, 

 that the brain forms a physiological exception to all the other organs 

 of the body, in that it is the seat of metaphysical manifestations, which 

 the physiologist has no concern with. It was perceived how digestion, 

 respiration, movement, etc., could be referred to the phenomena of 

 mechanism, of physics, and chemistry ; but it was not allowed that 

 thought, intelligence, and will, could be subjected to like explanation. 

 There is, it was said, a chasm between the organ and the function, 

 because the question is about metaphysical phenomena, and not at 

 all about physico-chemical mechanism. De Blainville, in his lectures 

 on zoology, laid great stress on the distinction between the organ and 

 the substratum. "In the organ," he said, "there is a visible and 

 necessary connection between anatomical structure and function ; in 

 the heart, the organ of circulation, the form and arrangement of valves 

 and orifices account perfectly for the circulation of the blood. In the 

 substratum, nothing like this is observable ; the brain is the substratum 

 of thought ; thought has its seat in the brain, but it cannot be inferred 

 from the brain's anatomy." Such considerations served as a founda- 

 tion for the belief that, in cases of insanity, the reason might be affected 

 essentially, as it was termed ; that is, without the existence of any 

 lesion in the substance of the brain. Even the converse was asserted, 

 and cases are cited in physiological treatises of the unimpaired mani- 

 festation of intelligence in persons with softened or indurated brains. 

 The progress of modern science has destroyed all such doctrines; yet 

 it must be admitted that those physiologists who have drawn from the 

 most delicate recent researches into the structure of the brain the con- 

 clusion that thought must be localized in a particular substance, or in 

 nerve-cells of a determinate form and order, have equally failed to 

 solve the problem, since they have done nothing more, in reality, than 

 to oppose materialistic theories to other spiritualistic theories. 



From what has been said, I shall draw the only conclusion which 

 legitimately results ; namely, that the mechanism of thought is unknown 

 to us a conclusion with which every one will probably agree. None 

 the less the fundamental question I have suggested exists ; for what 

 concerns us is to know whether our present ignorance on this subject 

 is a relative ignorance which will vanish with the progress of science, 

 or an absolute ignorance in the sense of its relating to a vital problem 

 which must forever remain beyond the ken of physiology. For myself, 

 I reject the latter opinion, because I deny that scientific truth can thus 



VOL. II. 5 



