The only part of the conduct of any one, for which he is amenable to society, is that which concerns others. In the part which merely concerns himself, his independence is, of right, absolute. Over himself, over his own body and mind, the individual is sovereign.

John Stuart Mill was a philosopher who had a lot of thoughts about a lot of things. He was a big believer in the power of free will and self-determination. He also believed that there should be equality for all people, regardless of race, gender, or religion. He was a fan of utilitarianism, which is all about maximizing happiness for the greatest number of people. He was an advocate for individual liberty and democracy. In short, he was a pretty cool dude.