So long as the mother, Ignorance, lives, it is not safe for Science the offspring, to divulge the hidden causes of things.

My aim is to say that the machinery of the heavens is not like a divine animal but like a clock (and anyone who believes a clock has a soul gives the work the honour due to its maker) and that in it almost all the variety of motions is from one very simple magnetic force acting on bodies, as in the clock all motions are from a very simple weight.

We do not ask for what useful purpose the birds do sing, for song is their pleasure since they were created for singing. Similarly, we ought not to ask why the human mind troubles to fathom the secrets of the heavens.

[God] is the kind Creator who brought forth nature out of nothing.

It may be well to wait a century for a reader, as God has waited six thousand years for an observer.

The roads by which men arrive at their insights into celestial matters seem to me almost as worthy of wonder as those matters in themselves.

Ships and sails proper for the heavenly air should be fashioned. Then there will also be people, who do not shrink from the dreary vastness of space.