xxxviii Centennial Anniversary 



part of the iinscientitic view of the universe. To the scientific 

 mind, the boundless complexity of the universe is dominated by a 

 supreme unity. One system of law, intelligible, forraulable, per- 

 vades the universe, through all its measureless extension in space 

 and time. The student of science may be theist or pantheist, 

 atheist or agnostic ; polytheist he can never be. 



What, then, let us ask ourselves, has been the contribution of 

 our century to the development of these three ideas, which char- 

 acterize the scientific view of nature : — the spatial extension of 

 the universe, the historic extension of the universe, and the unity 

 of the universe. 



The development of the idea of the extension of the universe 

 in space belongs mainly to earlier times than ours. The Greek 

 geometers acquired approximately correct notions of the size of 

 the earth and the distance of the moon. The Copernican astron- 

 omy in the sixteenth century shifted the center of the solar system 

 from the earth to the sun, and placed in truer perspective our view 

 of the celestial spheres. But, though astronomy, the oldest of 

 the sisterhood of the sciences, attained a somewhat mature devel- 

 opment centuries ago, it has in our own century thrown new light 

 upon the subject of the vastness of the universe. Tlie discovery 

 of N^eptune has greatly increased tlie area of the solar system ; 

 the measurement of the parallax of a few of the brightest and 

 presumably the nearest of the stars has rendered far more definite 

 our knowledge of the magnitude of the stellar universe ; and tele- 

 scopes of higher magnifying power than had been used before 

 have resolved many clusters of small and distant stars. 



If the development of the idea of the spatial extension of the 

 universe belongs mainly to an earlier period, the idea of its his- 

 toric extension belongs mainly to our century. It is true, indeed, 

 that Pythagoras and others of the ancient philosophers did not 

 fail to recognize indications of change in the surface of the earth. 

 And, in the beginning of the Kenaissance, we find Leonardo da 

 Yinci and others insisting that the fossils discovered in excava- 

 tions in the stratified rocks were proof of the former existence of 

 a sea teeming with marine life, where cultivated lands and popu- 

 lous cities had taken its place. Hutton's " Theory of the Earth," 

 which in an important sense marks the beginning of modern 

 geological theorizing, appeared in the Edinburgh Philosophical 



