clusions; being sooner or later infallibly punished for every over-hasty opinion, for every act of blind trust in appearances: such is the discipline 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.
Surely it appears as though mathematical research, too, which proceeds inductively to a greater extent than is commonly supposed, might have a like educating effect. 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 determination 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 mathematicians 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 generation. In this school the human mind has lost the habit of childish reverence 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 speculativism, 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 striving 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 Hellenes 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. Knowing well how immovably fixed are the bounds set to man's understand-
