34 



LECTURES AND ESS A YS 



IN our day grand generalisations have 

 been reached. The theory of the origin 

 of species is but one of them. Another, 

 of still wider grasp and more radical 

 significance, is the doctrine of the Con- 

 servation of Energy, the ultimate philo- 

 sophical issues of which are as yet 

 but dimly seen that doctrine which 

 " binds nature fast in fate," to an extent 

 not hitherto recognised, exacting from 

 every antecedent its equivalent conse- 

 quent, from every consequent its equiva- 

 lent antecedent, and bringing vital as 

 well as physical phenomena under the 

 dominion of that law of causal con- 

 nection which, so far as the human 

 understanding has yet pierced, asserts 

 itself everywhere in nature. Long in 

 advance of all definite experiment upon 

 the subject, the constancy and in- 

 destructibility of matter had been 

 affirmed ; and all subsequent experi- 

 ence justified the affirmation. Mayer 

 extended the attribute of indestructi- 

 bility to energy, applying it in the first 

 instance to inorganic, 1 and afterwards 

 with profound insight to organic nature. 

 The vegetable world, though drawing 

 all its nutriment from invisible sources, 

 was proved incompetent to generate 

 anew either matter or force. Its matter 

 is for the most part transmuted gas ; its 

 force transformed solar force. The 

 animal world was proved to be equally 

 uncreative, all its motive energies being 

 referred to the combustion of its food. 

 The activity of each animal, as a whole, 

 was proved to be the transferred activity 

 of its molecules. The muscles were 

 shown to be stores of mechanical energy, 

 potential until unlocked by the nerves, 

 and then resulting in muscular con- 

 tractions. The speed at which messages 

 fly to and fro along the nerves was deter- 

 mined by Helmholtz, and found to be, 

 not, as had been previously supposed, 



1 Dr. Berthold has shown that Leibnitz had 

 sound views regarding the conservation of energy 

 in inorganic nature. 



equal to that of light or electricity, but 

 less than the speed of sound less even 

 than that of an eagle. 



This was the work of the physicist : 

 then came the conquests of the com- 

 parative anatomist and physiologist, re- 

 vealing the structure of every animal and 

 the function of every organ in the whole 

 biological series, from the lowest zoo- 

 phyte up to man. The nervous system 

 had been made the object of profound 

 and continued study, the wonderful, and, 

 at bottom, entirely mysterious controlling 

 power which it exercises over the whole 

 organism, physical and mental, being 

 recognised more and more. Thought 

 could not be kept back from a subject 

 so profoundly suggestive. Besides the 

 physical life dealt with by Mr. Darwin, 

 there is a psychical life presenting similar 

 gradations, and asking equally for a 

 solution. How are the different grades 

 and orders of Mind to be accounted for? 

 What is the principle of growth of that 

 mysterious power which on our planet 

 culminates in Reason ? These are 

 questions which, though not thrusting 

 themselves so forcibly upon the attention 

 of the general public, had not only 

 occupied many reflecting minds, but had 

 been formally broached by one of them 

 before the Origin of Species appeared. 



With the mass of materials furnished 

 by the physicist and physiologist in his 

 hands, Mr. Herbert Spencer, twenty 

 years ago, sought to graft upon this basis 

 a system of psychology ; and two years 

 ago a second and greatly amplified 

 edition of his work appeared. Those 

 who have occupied themselves with the 

 beautiful experiments of Plateau will 

 remember that when two spherules of 

 olive-oil, suspended in a mixture of alcohol 

 and water of the same density as the oil, 

 are brought together, they do not imme- 

 diately unite. Something like a pellicle 

 appears to be formed around the drop?, 

 the rupture of which is immediately 

 followed by the coalescence of the 

 globules into one. There are organisms 

 whose vital actions are almost as purely 

 physical as the coalescence of such drops 



