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 
