The idea of duty, that recognition of something to be lived...

The idea of duty, that recognition of something to be lived for beyond the mere satisfaction of self, is to the moral life what the addition of a great central ganglion is to animal life. No man can begin to mould himself on a faith or an idea without rising to a higher order of experience: a principle of subordination, of self-mastery, has been introduced into his nature; he is no longer a mere bundle of impressions, desires, and impulses.