424 THE POPULAR SCIENCE MONTHLY. 



elusions ; being sooner or later infallibly punished for every over-hasty 

 opinion, for every act of blind trust in appearances : such is the dis- 

 cipline which accustoms the experimental scientist to be chary about 

 rapid and brilliant conquests ; to attack the truth which he fain would 

 discover by gradual approaches ; to test it as impartially as though his 

 aim were to prove the contrary ; and finally, when he is arrived at a 

 number of perhaps mutually contradictory facts held together by a 

 tissue of still obscure relations, and the whole looking toward sundry 

 possibilities whereof experience alone can decide which is stronger, 

 resignedly to keep that state of things present to his mind as the best 

 it is conceded him to know. 



Surel^^ it appears as though mathematical research, too, which 

 proceeds inductively to a greater extent than is commonly supposed, 

 might have a like educating efi'ect. It, too, possesses what is lacking 

 to metaphysical speculation, the sure means of determining whether its 

 judgments are correct or not. But the mathematician draws this deter- 

 mination from himself, and hence his occupation is less adapted than 

 experiment for weakening one's trust in speculation. Hence it is that 

 mankind could for two thousand years busy itself about problems in 

 mathematics, without ever curbing their propensity to speculation ; 

 hence, again, Descartes and Leibnitz, two of the greatest mathemati- 

 cians of the seventeenth century, were also the boldest metaphysicians 

 of the same period. 



Hardly two centuries have elapsed since chemists, physicists, and 

 physiologists went to work steadily and systematically, and already we 

 see the fruits of their teaching, as transmitted from generation to genera- 

 tion. In this school the human mind has lost the habit of childish rever- 

 ence and juvenile enthusiasm, grown up to the discretion of manhood, 

 and learned to comport itself modestly in presence of insoluble enigmas. 

 A new phase of its history is observable, partly in the decay of specula- 

 tivism, and partly in the style of philosophizing now adopted by the 

 best minds. 



The practice acquired by the man of science in the small warfare of 

 the laboratory fits him to deal with the great mystery of the universe. 

 The sti'iving which we observe in Leibnitz, toward constructing by 

 hook or by crook a universe wherein preconceptions inherited from 

 the childhood of the race are blended with the insight of an already 

 well-matured physico-mathematical mind, is a thing so foreign to the 

 man of science that he could no more think of adopting that point 

 of view than of adopting the mythological cosmogony of the Hel- 

 lenes or of the Brahmans. The complacent assurance with which 

 Leibnitz looks on his scheme as demonstrated, reminds him of similar 

 illusions in the beginning of his own scientific development, for in 

 the domain of mind, too, the biogenetic principle holds good. Know- 

 ing well how immovably fixed are the bounds set to man's understand- 



