“We must say that there are as many squares as there are numbers.”

In my studies of astronomy and philosophy I hold this opinion about the universe, that the Sun remains fixed in the centre of the circle of heavenly bodies, without changing its place; and the Earth, turning upon itself, moves round the Sun.

Who would dare assert that we know all there is to be known?

It is surely harmful to souls to make it a heresy to believe what is proved.

Knowing thyself, that is the greatest wisdom.

Philosophy is written in that great book which ever lies before our eyes. I mean the universe, but we cannot understand it if we do not first learn the language and grasp the symbols, in which it is written.

The nature of the human mind is such that unless it is stimulated by images of things acting upon it from without, all remembrance of them passes easily away.

We cannot teach people anything; we can only help them discover it within themselves.

Holy Scripture could never lie or err…its decrees are of absolute and inviolable truth.

Holy Scripture could never lie or err…its decrees are of absolute and inviolable truth.

Nature is written in mathematical language.

Nothing occurs contrary to nature except the impossible, and that never occurs.

God is known by nature in his works, and by doctrine in his revealed word.

In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual.

I’ve loved the stars too fondly to be fearful of the night.

The greatest wisdom is to get to know oneself.

I have never met a man so ignorant that I couldn’t learn something from him.