Doctors cut, burn, and torture the sick, and then demand of them an undeserved fee for such services.

I am what libraries and librarians have made me, with little assistance from a professor of Greek and poets

Presumption must be quenched even more than a fire.

Those who love wisdom must investigate many things

Could you tell night from day? No, I regard all such distinctions as logically impossible.

No one can step twice into the same river, nor touch mortal substance twice in the same condition. By the speed of its change, it scatters and gathers again.

You can never step in the same river twice.