1879.] Professor Huxley on Sensation. 115 



WEEKLY EVENING MEETING, 



Friday, March 7, 1879. 



Sir W. Frederick Pollock, Bart. M.A. Vice-President, 

 in the Chair. 



Professor Huxley, LL.D. F.R.S. 



Sensation and the Unity of Structure of Sensiferous Organs.* 



We are indebted to Descartes, who happened to be a physiologist 

 as well as a philosopher, for the first distinct enunciation of the 

 essential elements of the true theory of sensation. In later times, it 

 is not to the works of the philosophers, if Hartley and James Mill are 

 excepted, but to those of the physiologists, that we must turn for an 

 adequate account of the sensory process. Haller's luminous, though 

 summary, account of sensation in his admirable ' Primae Lineas,' the 

 first edition of which was printed in 1747, offers a striking contrast 

 to the prolixity and confusion of thought which pervade Reid's 

 ' Inquiry,' of seventeen years later date.f Even Sir William Hamilton, 

 learned historian and acute critic as he was, not only failed to appre- 

 hend the philosophical bearing of long-established physiological 

 truths ; but, when he affirmed that there is no reason to deny that 

 the mind feels at the finger points, and none to assert that the brain 

 is the sole organ of thought, he showed that he had not apprehended 

 the significance of the revolution commenced, two hundred years before 

 his time, by Descartes, and effectively followed up by Haller, Hartley, 

 and Bonnet in the middle of the last century. 



In truth, the theory of sensation, except in one point, is, at the 

 present moment, very much where Hartley, led by a hint of Sir Isaac 

 Newton's, left it, when, a hundred and twenty years since, the ' Ob- 

 servations on Man : his Frame, his Duty, and his Expectations,' was 



* The whole discourse is given in the ' Nineteenth Century ' for April, 1879. 



t In justice to Rcid, however, it should be stated that the chapters on Sensa- 

 tion in the 'Essays on tlie Intellectual Powers' (17S5) exhibit a great improve- 

 ment. He in, in fact, in advance of his commentator, as the note to Essay II. 

 chap. ii. p. 248, of Hamilton's edition shows. 



