Two forces rule the universe: light and gravity.

One has only the choice between God and idolatry. There is no other possibility. For the faculty of worship is in us, and it is either directed somewhere into this world, or into another.

Even if our efforts of attention seem for years to be producing no result, one day a light that is in exact proportion to them will flood the soul.

Sin is nothing else but the failure to recognize human wretchedness.

...nothing on earth can stop man from feeling himself born for liberty. Never, whatever may happen, can he accept servitude; for he is a thinking creature.

Mathematics alone make us feel the limits of our intelligence. For we can always suppose in the case of an experiment that it is inexplicable because we don't happen to have all the data. In mathematics we have all the data, brought together in the full light of demonstration, and yet we don't understand. We always come back to the contemplation of our human wretchedness. What force is in relation to our will, the impenetrable opacity of mathematics is in relation to our intelligence.

In what concerns divine things, belief is not appropriate. Only certainty will do. Anything less than certainty is unworthy of God.