SCIENTIFIC USE OF THE IMAGINATION 143 



the observed uniformity of nature is their only guide. 

 Within the long range of physical inquiry, they have 

 never discerned in nature the insertion of caprice. 

 Throughout this range, the laws of physical and intel- 

 lectual continuity have run side by side. Having thus 

 determined the elements of their curve in a world of ob- 

 servation and experiment, they prolong that curve into 

 an antecedent world, and accept as probable the unbroken 

 sequence of development from the nebula to the present 

 time. You never hear the really philosophical defenders 

 of the doctrine of Uniformity speaking of impossibilities 

 in nature. They never say, what they are constantly 

 charged with saying, that it is impossible for the Builder 

 of the universe to alter His work. Their business is not 

 with the possible, but the actual — not with a world which 

 might be, but with a world that is. This they explore 

 with a courage not unmixed with reverence, and accord- 

 ing to methods which, like the quality of a tree, are tested 

 by their fruits. They have but one desire — to know the 

 truth. They have but one fear — ^to believe a lie. And 

 if they know the strength of science, and rely upon it 

 with unswerving trust, they also know the limits beyond 

 which science ceases to be strong. They best know that 

 questions offer themselves to thought, which science, as 

 now prosecuted, has not even the tendency to solve. They 

 have as little fellowship with the atheist who says there 

 is no Grod, as with the theist who professes to know the 

 mind of God. "Two things," said Immanuel Kant, "fill 

 me with awe: the starry heavens, and the sense of moral 

 responsibility in man." And in his hours of health and 

 strength and sanity, when the stroke of action has ceased, 

 and the pause of reflection has set in, the scientific in- 



