The art of music is good, for the reason, among others, that it produces pleasure; but what proof is it possible to give that pleasure is good? If, then, it is asserted that there is a comprehensive formula, including all things which are in themselves good, and that whatever else is good, is not so as an end, but as a mean, the formula may be accepted or rejected, but is not a subject of what is commonly understood by proof.

Strong impulses are but another name for energy. Energy may be turned to bad uses; but more good may always be made of an energetic nature, than of an indolent and impassive one.

The ends of scientific classification are best answered, when the objects are formed into groups respecting which a greater number of general propositions can be made, and those propositions more important, than could be made respecting any other groups into which the same things could be distributed. ... A classification thus formed is properly scientific or philosophical, and is commonly called a Natural, in contradistinction to a Technical or Artificial, classification or arrangement.

The individual is not accountable to society for his actions in so far as these concern the interests of no person but himself.

If opponents of all important truths do not exist, it is indispensable to imagine them and supply them with the strongest arguments which the most skillful devil's advocate can conjure up.

Every one is degraded, whether aware of it or not, when other people, without consulting him, take upon themselves unlimited power to regulate his destiny.

A person whose desires and impulses are his own - are the expression of his own nature, as it has been developed and modified by his own culture - is said to have a character. One whose desires and impulses are not his own, has no character, no more than a steam-engine has character.