326 THE PRINCIPLES OF HEREDITY 



has a knowledge of botany and zoology not much more 

 profound nor useful intellectually than that possessed by the 

 average farmer or stockbreeder. Either he should be other- 

 wise employed during his earlier studies, or his later work 

 should be so modified as to link up with them. Facts, 

 scientific or other, have by themselves no intellectual or 

 scientific value. It is the recognition of the relationship 

 between facts in a natural group and between different 

 groups that confers the value. No doubt medical students, 

 in proportion to their intelligence, get a general notion of 

 the essential likenesses, which, amid distinguishing differ- 

 ences, bind together all living nature. But this result, if it 

 be the one sought, is attainable by direct teaching at a 

 hundredth part of the cost in time and labour. 1 



511. I suppose every man is apt to attach undue import- 

 ance to his special line of work. Just as Professor James' 

 hen cannot help thinking a nestful of eggs " the most utterly 

 fascinating and precious and never-to-be-too-much-sat-upon 

 object" in the world, so the classic, the physicist, or the 

 naturalist is prone to believe his particular study the most 

 admirable and important, and never-to-be-too-much-insisted- 

 on, belauded, and generally advocated in the world. Bearing 

 this well in mind it seems to me nevertheless that no kind 

 of study can be made to bear intellectual fruit of nearly such 

 value as the study of heredity. It lies at the root of every 

 science and every study connected with life from botany and 

 zoology to medicine, sociology or pedagogy. Who knows it 

 not knows not life except in its superficial aspects. He may 

 be a student of philosophy or a worker in biological science, 

 but in these days when heredity enters so much into 

 philosophy and links together so many biological sciences, 

 he cannot be a very effective thinker or worker. It furnishes 

 a master-key to the more tremendous events of history, and 



1 " Thus there gradually accumulated a new mass of material ; 

 investigation became more and more specialized and the danger became 

 imminent that workers in the various departments would be unable to 

 understand one another in their special researches. There was lack of 

 any unifying bond, for workers had lost sight of the general problem in 

 which all branches of science meet, and through which alone they can 

 be united into a general science of biology. The time had come for 

 again combining and correlating the details, lest they should grow into 

 an unconnected chaos, through which it would be impossible to find 

 one's way, because no one could overlook it and grasp it as a whole. In 

 a word, it was high time to return to general questions." (The Evolution 

 Theory, Weismann, English Translation, p. 27.) All this, written of 

 the naturalists of the pre-Darwinian era, is very true of the medical 

 men of the present day, whose science, after all, is a biological one. 



