The present age is not merely an epoch of discovery; it is also a period of revision of the various elements of knowledge. Having recognised that there are no phenomena of which the first cause is still accessible, science has resumed the examination of her ancient certitudes, and has proved their fragility. To-day she sees her ancient principles vanishing one by one. Mechanics is losing its axioms, and matter, formerly the eternal substratum of the worlds, becomes a simple aggregate of ephemeral forces in transitory condensation... Time has calmed passions, numerous documents have gradually emerged from the archives, and the historian is learning to interpret them independently.But it is perhaps modern psychology that has most effectually influenced our ideas, by enabling us more surely to read men and the motives of their conduct...