John Stuart Mill 
On Liberty 

At the time it was published in 1859, John Stuart Mill’s On Liberty was a radical and controversial work; it argued for the right of individuals to possess freedom from the state in moral and economic matters. Mill declares that "Over himself, over his own body and mind, the individual is sovereign", contrasting this with the "tyranny of the majority." He states that an individual can do anything they like as long as it doesn’t harm another — the well-known "harm principle". On Liberty had a huge impact and has remained a relevant philosophical and political text today.