TAIT'S SECOND REPLY 285 



be framed in any other than words of the highest abstractness " ; and by way 

 of a general enquiry into mental idiosyncrasies proceeded to put together in 

 one group the two mathematicians Kirkman and Tail and two literary 

 men, a North American Reviewer and Matthew Arnold. We are told 

 (p. 570) that 



" men of letters, dieted in their early days on grammars and lexicons and in 

 their later days occupied with belles lettres, Biography and a History made up 

 mainly of personalities, are by their education and course of life left almost without 



scientific ideas of a definite kind The mathematician too and the mathematical 



physicist, occupied exclusively with the phenomena of number space and time, or, in 

 dealing with forces, dealing with them in the abstract, carry on their researches in 

 such ways as may, and often do, leave them quite unconscious of the traits 

 exhibited by the general transformations which things, individually and in their 

 totality, undergo." 



These exhibit "certain defects of judgment... to which the analytical 

 habit, unqualified by the synthetical habit, leads." Much of which seems to 

 be beside the mark. Tait certainly was not occupied exclusively with the 

 phenomena of number, space and time. His was a mind intuitively physical. 

 He was in experimental touch with things as they are in a way to which 

 Spencer was an absolute stranger. As for lack of scientific ideas of a definite 

 kind, no better examples can be found than in First Principles, especially 

 in the chapter on the Instability of the Homogeneous. Enough has been 

 given of Herbert Spencer's own words to enable us to appreciate Tail's 

 rejoinder. This was given as part of his opening lecture in 1880, and 

 appeared in Nature, Nov. 25, the same year; but it will suffice to reproduce 

 only those parts which are not a repetition of previous letters. 



Mr Spencer has quite recently published a species of analytical enquiry into 

 my " mental peculiarities," " idiosyncrasies of thought," " habits of mind," " mental 

 traits," and what not. From his illustrative quotations it appears that some or all 

 of these are manifested wherever there are differences between myself and my critic 

 in the points of view from which we regard the elements of science. Hence they 

 are not properly personal questions at all, but questions specially fitted for discussion 

 here and now. I may, therefore, commence by enquiring what species of "mental 

 peculiarity" my critic himself exhibited when he seriously asked me whether I had 

 proved by experiment that a thing might have been what it is not ! ! 



The title of Mr Spencer's pamphlet informs us that it deals with Criticisms ; 

 and I am the first of the subjects brought up in it for vivisection, albeit I have been 

 guilty (on Mr Spencer's own showing) only of " tacitly " expressing an opinion ! Surely 

 my vivisector exhibits here also some kind of " mental peculiarity." Does a man 



