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SCIENCE 



[N. S. Vol. XXXVIII. No. 982 



minds of wiser men. The originator is then 

 often either forgotten or condemned. But 

 the idea is none the less potent and valu- 

 able. Now amongst the leading ideas of the 

 JVaturphilosophie were a number which 

 have since proved to be of no small impor- 

 tance in the sciences. The first of these 

 ideas is a vague and an ancient, but a 

 powerful idea, which the Naturphilosophie 

 simply translated into more modern terms, 

 and so prepared, as it were, for use in the 

 new century. This is the idea that all 

 science must strive to be one, that special 

 research must be governed, in the long run, 

 by the aim to bring truth into unity, and 

 that unity is always beneath all sorts of 

 plurality, as the basis and the meaning 

 thereof. 



I have said that this idea is vague. It 

 always remains vague until you discover, 

 in some field of knowledge, in what sense 

 it is true. Then it always appears very 

 luminous, and you rejoice in it. I have 

 said that this idea of the essential unity 

 of truth is ancient. The Greeks began 

 with it. The sages and the saints lived 

 and died for the sake of it. The church 

 tried to secure its recognition by means of 

 a catholic creed. The medieval mystics 

 revelled in it. Yet many heretics also 

 gloried in it as their own peculiar posses- 

 sion, and Giordano Bruno was burned for 

 the sake of it. The modern philosophers 

 renewed the idea. Spinoza reared a beau- 

 tiful monument of thought in its honor. 

 The Naturphilosophen spent their strength 

 in proclaiming it. And since their time 

 modern science, in the later theory of en- 

 ergy, in the doctrine of evolution, in vari- 

 ous other ways which I need not enumer- 

 ate, has illustrated it with unexpected 

 brilliancy, and with marvelous precision. 



Now this idea, that the unity of the truth 

 is deeper than is even the most baffling 

 variety of phenomena — what does this idea 

 mean? In what sense is it a leading idea 



of science as well as of religion and philos- 

 ophy? To this question it is easy to an- 

 swer that by the unity of truth one means 

 nothing that one would have a right to 

 assert of any world that is foreign to hu- 

 man thought. One means only that man 

 always strives and must strive for his own 

 rational purposes, to get his ideas into 

 some sort of rational connection, and to 

 view them as a system. The demand that 

 truth shall hang together and be one whole 

 is man's demand. His reason restlessly 

 searches for such unity, and is discontented 

 until the quest succeeds. This is indeed 

 the fact. Man's reason demands that 

 man's experience shall be viewed as a con- 

 nected whole. Well — this, apart from 

 their obscurities, is precisely what the Na- 

 turphilosophen taught. Since they were 

 idealists, they did not view the world as 

 anything foreign to the human reason. 

 Hence they founded their interpretation 

 of the unity of things expressly upon the 

 needs and the interpretation of man's own 

 rational nature. Vague as their thinking 

 was, it did therefore express a decidedly 

 sound consciousness of the motives that 

 lead us to seek for unity in the world af 

 scientific truth. Now you may rightly say 

 that the Naturphilosophen had no right to 

 prescribe to nature, as they did, just how 

 her laws should be interpreted even before 

 they had been adequately observed. But, 

 on the other hand, men generally do not 

 find until they eagerly seek. The Natur- 

 philosophen set their countrymen eagerly 

 seeking for unity in nature. They special- 

 ized the vaguer ancient idea of unity by 

 giving it conscious relations to the newer 

 fields of natural science. I am tolerably 

 certain that the eager search thus begun 

 had a very real, even if a mainly indirect, 

 influence upon the successful prosecution 

 of the search which so soon followed the 

 decay of the Naturphilosophie itself. I 



