Astronomy, that micography of heaven, is the most magnificent of the sciences. ... Astronomy has its clear side and its luminous side; on its clear side it is tinctured with algebra, on its luminous side with poetry.

One resists the invasion of armies; one does not resist the invasion of ideas.

To lie a little is not possible: he who lies, lies the whole lie.

Let us leave to the brain what belongs to it, and agree that the work of the men of genius is of the superhuman, the offspring of man.

To know, to think, to dream. That is everything.

The soul in the darkness sins, but the real sinner is he who caused the darkness.

Let us admit, without bitterness, that the individual has his distinct interests and can, without felony, stipulate for those interests and defend them. The present has its pardonable amount of egotism; momentary life has its claims, and cannot be expected to sacrifice itself incessantly to the future. The generation which is in its turn passing over the earth is not forced to abridge its life for the sake of the generations, its equals after all, whose turn shall come later on.