"[T]here is a sphere of action in which society, as distinguished from the individual, has, if any, only an indirect interest; comprehending all that portion of a person's life and conduct which affects only himself, or, if it also affects others, only with their free, voluntary, and undeceived consent and participation. When I say only himself, I mean directly, and in the first instance: for whatever affects himself, may affect others through himself; and the objection which may be grounded on this contingency, will receive consideration in the sequel. This, then, is the appropriate region of human liberty."
- John Stuart Mill