We must infer that a plant or animal of any species, is made up of special units, in all of which there dwells the intrinsic aptitude to aggregate into the form of that species: just as in the atoms of a salt, there dwells the intrinsic aptitude to crystallize in a particular way.‎

When a man's knowledge is not in order, the more of it he has the greater will be his confusion.

Our lives are universally shortened by our ignorance.

In science the important thing is to modify and change one's ideas as science advances.

Let men learn that a legislature is not 'our God upon earth,' though, by the authority they ascribe to it, and the things they expect from it, they would seem to think it is. Let them learn rather that it is an institution serving a purely temporary purpose, whose power, when not stolen, is at the best borrowed.

When men hire themselves out to shoot other men to order, asking nothing about the justice of their cause, I don't care if they are shot themselves.

The ultimate result of shielding men from the effects of folly, is to fill the world with fools.