History is the only laboratory we have in which to test the consequences of thought.

Humans feel at home in a world of things, whose essences and laws it can grasp and define in terms of concepts but shy and ill at ease in a world of existences, because to exist is an act, not a thing.

Let us ... quietly accept our times, with the firm conviction that just as much good can be done today as at any time in the past, provided only that we have the will and the way to do it.

Man is not a mind that thinks, but a being who knows other beings as true, who loves them as good and who enjoys them as beautiful. For all that which is, down to the humblest form of existence, exhibits the inseparable privileges of being, which are truth, goodness, and beauty.

If our previous analyses are correct, they all point to the same conclusion, that metaphysical adventures are doomed to fail when their authors substitute the fundamental concepts of any particular science for those of metaphysics.