292 SCIENTIFIC THOUGHT. 



cultivation of his youth awoke in him the speculative 

 love of symmetry and system ; but a singular clearness 

 and precision of the classifying power, which he possessed 

 as a native talent, was exercised and developed by exactly 

 those geological facts among which his philosophical task 

 lay. Some of the advances which he made had been 

 entered upon by others who preceded him; but of all 

 this he was ignorant, and perhaps went on more steadily 

 and eagerly to work out his own ideas from the persuasion 

 that they were entirely his own." In what he did and 

 published, beginning with the year 1790, "we see great 

 vividness of thought and activity of mind unfolding itself 

 exactly in proportion to the facts with which it had to 

 deal." 1 



About the same time that geological studies received a 

 great impetus in this country from two distinct centres 

 the philosophical teaching in the Scotch metropolis, and 

 the more empirical labours of the Geological Society a 

 signal discovery in another line marked a great step in 

 52. anatomy and physiology. This was Charles Bell's dis- 



Charles Bell. . 



covery, in the year 1807, of the difference between sensory 

 and motor nerves, "doubtless the most important accession 

 to physiological knowledge since the time of Harvey." 2 



1 Whewell, loc. cit. , p. 423. 



2 This statement, taken from Dr 

 Henry's ' Report of the British As- 

 sociation,' vol. vi., and repeated by 

 Whewell (loc. cit., vol. iii. p. 352), 

 probably requires a correction, since 

 Du Bois-Reymond and others have 

 placed in their true historical posi- 

 tion the great merits of Descartes, 

 who by the discovery of the principle 

 of "reflex action" "did for the 

 physiology of motion and sensation 



the circulation of the blood, and 

 opened up that road to the me- 

 chanical theory of these processes 

 which has been followed by all his 

 successors" (Huxley hi this address 

 to the British Association at Bel- 

 fast, 1874; reprinted in 'Science 

 and Culture, &c.,' p. 200, &c.) The 

 first enunciation of the principle of 

 reflex action had been variously 

 ascribed to Joh. Miiller, Prochaska, 

 Willis, till Du Bois-Reymond in his 



that which Harvey had done for I most interesting ' Gedachtnissrede 



