io6 THE POPULAR SCIENCE MONTHLY. 



so that the beginning of the one impression is inseparably associated 

 with the departure or cessation of the other. Thus our inability to 

 form a conception always arises from our being compelled to form 

 another contradictory to it." 



Our inability to conceive a round square due to the fact " that in 

 our uniform experience, at the instant when a thing begins to be 

 round, it ceases to be square," and to the inseparable association be- 

 tween incipient roundness and departing squareness ! Whether any 

 one has ever had such experience as is here described, I do not know ; 

 but, if he has, I am confident that, even after being reenforced by a 

 large inheritance of ancestral experience in the light of the modern 

 theory of evolution, it will prove insufficient to account for the insep- 

 arable association which Mill brings into play. The simple truth is, 

 that a round square is an absurdity, a contradiction in terms. A 

 square is a figure bounded by four equal straight lines intersecting at 

 right angles ; a round figure is a figure bounded by a curve ; and the 

 oldest definition of a curve is that of " a line which is neither a straight 

 line, nor made up of straight lines." 



It ought to be said that there are expressions in the same chapter 

 of Mill's book, from which I have just quoted, which show that the 

 author was very ill at ease in the presence of his own theory. For in- 

 stance, he says (ib., p. 88) : " These things are literally inconceivable 

 to us, our minds and our experience being what they are. Whether 

 they would be inconceivable if our minds were the same, but our ex- 

 perience different, is open to discussion. A distinction may be made 

 which, I think, will be found pertinent to the question. That the 

 same thing should at once be and not be — that identically the same 

 statement should be both true and false — is not only inconceivable to 

 us, but we cannot conceive that it could be made conceivable" 



That so clear and vigorous a thinker* as Mill should have been 

 capable (especially when he was grappling with the thoughts of a 

 man like Sir W. Hamilton) of writing these sentences, is indeed won- 

 derful. First, he denies that inconceivability is, in any sense or in any 

 case, a test of truth or reality ; but then he says it may be otherwise, 

 if the inconceivability itself is inconceivable ! That is to say : a wit- 

 ness is utterly untrustworthy ; but, when he makes a declaration re- 

 specting his own trustworthiness, he ought to be believed ! 



That the whole theory of inseparable association, as here advanced 

 and applied by Mill, is without foundation, it being impossible, under 

 his theory, to know what the experience of his numerous readers has 

 been, except again by experience which he cannot have had, since 

 most of these readers were utterly unknown to him — that all attempts 

 to argue questions with any one on such a basis are supremely foolish, 

 Mill being bound, by his own doctrine, to accept the answer, " My 

 experience has been otherwise," as conclusive — that this theory is 

 suicidal and subversive of itself, and that every earnest sentence Mill 



