That hemisphere of the moon which faces us is better known than the earth itself; its vast desert plains have been surveyed to within a few acres; its mountains and craters have been measured to within a few yards; while on the earth's surface there are 30,000,000 square kilometres (sixty times the extent of France), upon which the foot of man has never trod, which the eye of man has never seen.

The universe is so immense that it appears immutable, and that the duration of a planet such as that of the earth is only a chapter, less than that, a phrase, less still, only a word of the universe’s history.

The present inhabitation of Mars be a race superior to ours is very probable.

Le Verrier-without leaving his study, without even looking at the sky-had found the unknown planet [Neptune] solely by mathematical calculation, and, as it were, touched it with the tip of his pen!

Lightning is like an elementary spirit, eccentric or rational, clever or silly, passing from one extreme to the other.

The supernatural does not exist.

Men have had the vanity to pretend that the whole creation was made for them, while in reality the whole creation does not suspect their existence.