You do not settle whether an argument is justified by merely showing that it is of some use. The distinction is not between useful and useless experiments but between barbarous and civilized behaviour. Vivisection is a social evil because if it advances human knowledge, it does so at the expense of human character.
If you don't begin to be a revolutionist at the age of twenty, then at fifty you will be a most impossible old fossil. If you area red revolutionary at the age of twenty, you have some chance of being up-to-date when you are forty!
With the single exception of Homer, there is no eminent writer, not even Sir Walter Scott, whom I can despise so entirely as I despise Shakespeare when I measure my mind against his. . . . It would positively be a relief to me to dig him up and throw stones at him.
People always get tired of one another. I grow tired of myself whenever I am left alone for ten minutes, and I am certain that I am fonder of myself than anyone can be of another person.
In truth , mankind cannot be saved from without, by schoolmasters or any other sort of masters: it can only be lamed and enslaved by them. It is said that if you wash a cat it will never again wash itself. This may or may not be true : what is certain is that if you teach a man anything he will never learn it; and if you cure him of a disease he will be unable to cure himself the next time it attacks him.