See now the power of truth.

I wish, my dear Kepler, that we could have a good laugh together at the extraordinary stupidity of the mob. What do you think of the foremost philosophers of this University? In spite of my oft-repeated efforts and invitations, they have refused, with the obstinacy of a glutted adder, to look at the planets or the Moon or my glass [telescope].

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

In time you may discover everything that can be discovered, and still your progress will only be progress away from humanity. The distance between you and them can one day become so great that your joyous cry over some new gain could be answered by an universal shriek of horror.

Nonetheless, it moves.

I would say here something that was heard from an ecclesiastic of the most eminent degree: The intention of the Holy Spirit is to teach us how one goes to heaven, not how the heavens go.

And believe me, if I were again beginning my studies, I should follow the advice of Plato and start with the mathematical sciences, which proceed very cautiously and admit nothing as established until it has been rigorously demonstrated.