Reason and Instinct. 6433 



hastily to conclude that this or that quality cannot be then because 

 we fail to recognise it at the outset of the inquiry. For we shall find, 

 from time to time, certain Instincts themselves, under the influence 

 of altered circumstances, fading away, almost dying out ; only to 

 recover their pristine force when the altered circumstances revert to 

 their former type; and besides that, new habits and manners — 

 certainly not due to Instinct at all — growing up and obtaining perma- 

 nent subsistence, in cases where nothing of the sort would have been 

 looked for originally, and most certainly not found if looked for. 



And now we have reached a point at which it may be permitted us 

 to advert to the confirmation secured to our theory by the successive 

 developments of the brain in the several classes of animals; noticing 

 at the same time their corresponding psychical development, as we 

 successively proceed from the lower to the highest classes of ani- 

 mated life. 



I suppose that it can scarcely be seriously objected that the com- 

 parative Anatomy of the brain can have no connection with, or bearing 

 on, the enquiry in which we are engaged. It seems as impossible to 

 question the fact that the brain is the material organ through which, 

 in the animal, Instinct acts, as that it is the organ through which, 

 when more highly developed, true Reason or Intellect acts. Anatomy 

 shows that from the simplest, indeed, most rudimentary form of brain 

 in the lower animals, to its highest, most complete development, there 

 is a mechanical contrivance and arrangement employed, identical as 

 to its general principle, in all from the lowest to the highest ; differing 

 only in what may be called the degree of nicety and completeness and 

 finish with which the plan is carried out in each successive step. In 

 every creature in existence possessing a brain, however rudimentary, 

 there are a series of nerves of sensation (few, or inconceivably many, 

 as the case may be) which are the telegraphs to the brain of external 

 incident ; and there are nerves of motion, which are telegraphs from 

 the brain, of instruction and direction for the various organs which 

 are elements in the composition of each several creature's physical 

 frame. And in addition to this principle of general identity, experiment 

 steps in and declares authoritatively not only that there is no apparent 

 or discernible difference between the uses and the operation of the 

 nervous system in the highest animal and in the lowest, but that also 

 such and such parts of its cerebral centre may be demonstrated to have 

 and to fulfil such and such functions. So that, in point of fact, we 

 may at once assume it to be placed quite beyond controversy that the 

 entire brain, or some part or parts of it— the variation between the 



XVII. R 



