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

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.

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.

Formulae are the anaesthetics of thought, not its stimulants and to make any one think is far better worth while than cramming him with ill-considered, and therefore indigestible, learning.

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.

Imagination is as vital to any advance in science as learning and precision are essential for starting points.

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.