Ixxxiv INTRODUCTION 



of science is far from the grosser materialism of the common 

 beliefs. 



Lamarck believed that " emotions of the inner feeling " 

 might be aroused either through sensation or through thought. 

 The physical characteristic of an emotion aroused by sensa- 

 tion is simply an agitation or " emotion " of the nervous 

 fluid in the nucleus. An emotion differs from a sensation 

 in that it involves no reaction from other sensitive nerves. 

 The original agitation is conveyed to the nucleus by a single 

 nerve, as in a sensation ; and the commotion or emotion 

 there produced has no further active effect. If it acts on 

 any nerves, it is upon motor nerves which give rise to muscular 

 action. Every need (besoin) excites an emotion, either 

 through the medium of sensation or of thought. The 

 emotion, then acting upon the motor nerves, gives rise to 

 just those actions necessary for the satisfaction of the 

 need felt. 



Lamarck explains habit by the tendency of the subtle 

 fluids constantly to traverse the same routes through the 

 organism. The first passage of the fluids facilitates sub- 

 sequent passages along the same channel, so that similar 

 actions tend to be repeated. He regarded instinct as originat- 

 ing in acquired habits. The habit once acquired would, 

 according to Lamarck, be inherited, and in course of 

 time become an instinct. In both these doctrines, he 

 anticipated two of the leading principles in Spencer's 

 Principles of Psychology. The idea of instinct as habit, 

 acquired and inherited, is indeed almost universally attri- 

 buted to Spencer. There is but little interest in determin- 

 ing the priority, however ; for the idea itself is certainly 

 erroneous. 



Lamarck also based upon his nervous fluid a theory of 

 fatigue. The fluid, he says, is used up while functioning, 

 and has to be made good. Hence the necessity for rest 

 before further activities can be undertaken. 



Lamarck regarded the will as an intellectual faculty, 

 though not in the first rank of importance. Here again he 



