The least movement is of importance to all nature. The entire ocean is affected by a pebble.

Piety is different from superstition. To carry piety to the extent of superstition is to destroy it. The heretics reproach us with this superstitious submission. It is doing what they reproach us with.

Those honor nature well, who teach that she can speak on everything...

To find recreation in amusements is not happiness; for this joy springs from alien and extrinsic sources, and is therefore dependent upon and subject to interruption by a thousand accidents, which may minister inevitable affliction.

When I consider the small span of my life absorbed in the eternity of all time, or the small part of space which I can touch or see engulfed by the infinite immensity of spaces that I know not and that know me not, I am frightened and astonished to see myself here instead of there … now instead of then.

Kind words do not cost much. They never blister the tongue or lips. They make other people good-natured. They also produce their own image on men's souls, and a beautiful image it is.

The eternal silence of these infinite spaces frightens me.