The ludicrous state of solid geometry made me pass over this branch.

Courage is knowing what to fear.

What is at issue is the conversion of the mind from the twilight of error to the truth, that climb up into the real world which we shall call true philosophy.

The physician, to the extent he is a physician, considers only the good of the patient in what he prescribes, and his own not at all

If there is a good and wise God, then there also exists a progress of humanity toward perfection.

There is far greater peril in buying knowledge than in buying meat and drink.

Those who have a natural talent for calculation are generally quick-witted at every other kind of knowledge; and even the dull, if they have had an arithmetical training, although they may derive no other advantage from it, always become much quicker than they would have been.