If astronomy teaches anything, it teaches that man is but a detail in the evolution of the universe, and the resemblant though diverse details are inevitably to be expected in the hosts of orbs around him. He learns that, though he will probably never find his double anywhere, he is destined to discover any number of cousins scattered through space.

Imagination is as vital to any advance in science as learning and precision are essential for starting points. Let me warn you to beware of two opposite errors: of letting your imagination soar unballasted by facts, but on the other hand, of shackling it so solidly that it loses all incentive to rise.

Bright points in the sky or a blow on the head will equally cause one to see stars.

The whole object of science is to synthesize, and so simplify; and did we but know the uttermost of a subject we could make it singularly clear.

Ever since celestial mechanics in the skillful hands of Leverrier and Adams led to the world-amazed discovery of Neptune, a belief has existed begotten of that success that still other planets lay beyond, only waiting to be found.

That Mars is inhabited by beings of some sort or other we may consider as certain as it is uncertain what these beings may be.

Now when we think that each of these stars is probably the centre of a solar system grander than our own, we cannot seriously take ourselves to be the only minds in it all.