28 NATURE AND LIFE. 



mense chasm which Descartes filled by the conception of 

 ether, the most marvelous of modern creations. Aristotle's 

 dynamism was vague, and Leibnitz gave it precision by 

 showing that the type and the fountain of force is and can 

 be nothing else than mind. He lifted the conception of 

 force to the conception of soul. And what has been done 

 in our days ? We have computed the motion, we have 

 detected the action, of that subtile ether ; we have proved 

 the absolute imperishableness of force ; we have shown by 

 many instances the fundamental identity of the appetitive 

 and elective powers of chemistry and crystallography with 

 those which psychology reveals. Here is the future of 

 science and of metaphysics. Both will henceforth follow 

 in their development the very course they have held to 

 since the first day; they have never, like Penelope, de- 

 stroyed yesterday's work the day after. They have pur- 

 sued the same end with continuous advance, that is, the 

 conception of invisible principles, and of the ideal essence 

 of things. This end will remain the ever-unattained goal of 

 their ambition. The farther we shall advance, the more 

 clearly and convincingly will they persist in defining those 

 primal forces and elementary activities half guessed at from 

 the very dawn of thought. Never false to themselves, they 

 will always, at whatever point in history we appeal to 

 them, represent the human soul unchanging in its nature, 

 its powers, and its hopes. Let them never muse over the 

 mournful question whether the work of the past will not 

 vanish at some time without leaving a trace. All of it will 

 survive, and from this confidence those who strive to in- 

 crease the sum of knowledge draw their courage and con- 

 solation. 



The conceptions of matter now entertained agree not 

 only with the boldest deductions and most splendid dis- 

 coveries of contemporary science, as well as with the oldest 

 truths and the most instinctive faiths of humanity, but also 



