"Ether is, in effect, a merely hypothetical entity, valuable only in so far as it explains that which by means of it we endeavor to explain — light, electricity, or universal gravitation — and only so far as these facts cannot be explained in any other way. In like manner the idea of God is also an hypothesis, valuable only in so far as it enables us to explain that which by means of it we endeavor to explain — the essence and existence of the Universe — and only so long as these cannot be explained in any other way. And since in reality we explain the Universe neither better nor worse with this idea than without it, the idea of God, the supreme petitio principii, is valueless."

“Faith feels itself secure neither with universal consent, nor with tradition, nor with authority. It seeks support of its enemy, reason.”

“There are, in fact, people who appear to think only with the brain, or with whatever may be the specific thinking organ; while others think with all the body and all the soul, with the blood, with the marrow of the bones, with the heart, with the lungs, with the belly, with the life. And the people who think only with the brain develop into definition-mongers; they become the professionals of thought.”

“Just as eunuchs will never know aesthetics as applied to the selection of beautiful women, so neither will pure rationalists ever know ethics, nor will they ever succeed in defining happiness, for happiness is a thing that is lived and felt, not a thing that is reasoned or defined.”

“And the upshot of all this," so I have been told more than once and by more than one person, "will be simply that all you will succeed in doing will be to drive people to the wildest Catholicism." And I have been accused of being a reactionary and even a Jesuit. Be it so! ...I know very well it is madness to seek to turn the waters of the river back to their source, and that it is only the ignorant who seek to find in the past a remedy for their present ills; but I know too that anyone who fights for any ideal whatever, although his ideal may seem to lie in the past, is driving the world on to the future, and that the only reactionaries are those who find themselves at home in the present. Every supposed restoration of the past is a creation of the future, and if the past which it is sought to restore is a dream, something imperfectly known, so much the better.”

“In books of psychology written from the spiritualist point of view, it is customary to begin the discussion of the existence of the soul as a simple substance, separable from the body, after this style: There is in me a principle which thinks, wills and feels... Now this implies a begging of the question. For it is far from being an immediate truth that there is in me such a principle; the immediate truth is that I think, will and feel. And I — the I that thinks, wills and feels — am immediately my living body with the states of consciousness which it sustains. It is my living body that thinks, wills and feels.”

“And thus the soul pities God and feels itself pitied by him; loves Him and feels loved by Him, sheltering its misery in the bosom of the eternal and infinite misery, which, in eternalizing itself and infinitizing itself, is the supreme happiness itself.”