494 HEREDITY AND SELECTION IN SOCIOLOGY 



theory also, that science has constituted, and will continue to 

 constitute, one of the highest forms of human expansion. 

 Conflict, as we have said, is to be understood not merely as mean- 

 ing the employment of brute force, but as including the conflicts 

 which take place within the human breast ; for these are none the 

 less intense because they are invisible, and they constitute a 

 factor in human evolution, the importance of which it woiild 

 be dif&cult to over-estimate. And to this intensifying of an 

 important factor in the progress of the human intellect theoretical 

 science has contributed the Uon's share. If the intellectual 

 condition of the Middle Ages may be described as being the 

 agreement of the ignorant, the present condition of intellectual 

 development is that of the disagreement of the thoughtful ; 

 and this second phase of intellectual development, inestimably 

 beneficial to intellectual progress, has been brought about chiefly 

 by the discoveries of science in its theoretical domain, as distinct 

 from the domain of apphed science. By causing disagreement, 

 science has stimulated thought ; by stimulating thought it 

 has stimulated discovery ; and thus it has contributed power- 

 fully to that wonderful expansion of the human intellect 

 which we have witnessed in the latter half of the nineteenth 

 century. 



To take a single conspicuous example, let us turn to the science 

 of Life — to biology. Comparative physiology, which embraces 

 all the phenomena of life, from the lowest animals up to man, 

 is a triumph of the nineteenth century. Passing from the great 

 work accomplished by its founder, Johannes Miiller, we come 

 to the researches of Schleiden on the cellular composition of 

 plants, and to those of Schwann on the cellular composition of 

 animal tissue. Contemporary with the labours of Johannes 

 Miiller we find those of Von Baer, whose discovery of the ovum 

 and of its development into a hollow sphere with Uquid contents, 

 the wall of which forms the slender germinal membrane 

 (Blastoderm), laid the foundation of embryology. The dis- 



