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.

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

Lightning seems a thought, which instead of being attached to a brain, is attached to an electric current.

The supernatural does not exist.

What, then, is this blue sky, which certainly does exist, and which veils from us the stars during the day?

May we attribute to the color of the herbage and plants, which no doubt clothe the plains of Mars, the characteristic hue of that planet, which is noticeable by the naked eye, and which led the ancients to personify it as a warrior?

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.