18 THE POPULAR SCIENCE MONTHLY, 



was Kant's own meaning, when he withheld from chemistry the title 

 of science, and relegated it among experimental sciences. It is not a 

 little noteworthy that in our own times chemistry, being forced, by 

 the discovery of the doctrine of substitution, to surrender electro-chem- 

 ical dualism, has been apparently still further removed from the grade 

 of a science, in this sense of the word. 



K we were to suppose all changes in the physical world resolved 

 into atomic motions, produced by constant central forces, then we 

 should know the universe scientifically. The condition of the world 

 at any given moment would then appear to be the direct result of its 

 condition in the preceding moment, and the direct cause of its condi- 

 tion in the subsequent moment. Law and chance would be only dif- 

 ferent names for mechanical necessity. Nay, we may conceive of a 

 degree of natural science wherein the whole process of the universe 

 might be represented by one mathematical formula, by one infinite sys- 

 tem of simultaneous differential equations, which should give the loca- 

 tion, the direction of movement, and the velocity, of each atom in the 

 universe at each instant. " A mind," says Laplace, " which at a given 

 instant should know all the forces acting in Nature, as also the re- 

 spective situation of the beings of which it consists, provided-its pow- 

 ers were sufiiciently vast to analyze all these data, could embrace in 

 one formula the movements of the largest bodies in the universe, and 

 those of the smallest atom ; nothing would be uncertain for such a 

 mind, and the future, like the past, would be present to its eyes. The 

 human intellect offers, in the perfection to which it has brought 

 astronomy, a faint idea of what such a mind would be." 



Indeed, just as in lunar equations the astronomer need give but a 

 negative value to time, in order to determine whether, when Pericles 

 embarked for Epidaurus, the sun was eclipsed for the Piraeus, so oould 

 the mind imagined by Laplace, by suitable application of its universal 

 formula, tell us who was the Man in the Iron Mask, or how the President 

 was lost. As the astronomer foretells the day whereon years hence a 

 comet emerges again out of the depths of space into the heavens, so 

 could that mind by its equations determine the day whereon the Greek 

 cross shall glitter from the mosque of St. Sophia, or when England 

 shall have consumed the last of her coals. If in his universal formula 

 he set down t= — aD, he could discover the mysterious primeval condi- 

 tion of all things. He would in the boundless space see matter al- 

 ready in motion, or unequally distributed, for, were the distribution 

 equable, there could never be disturbance of equilibrium. Suppose 

 he lets t grow ad infinitum in the positive sense, then he could tell 

 whether Carnot's theorem threatens the universe with icy immobility 

 in finite or only in infinite time. For such a mind the hairs of our 

 heads would be numbered, and without his knowledge no sparrow 

 could fall to the ground. Being a seer expert both in the past and 

 the future, for him, as D'Alembert, in the Introduction to the Ency- 



