From Mill’s On Liberty:
The only freedom which deserves the name is that of pursuing our own good in our own way, so long as we do not attempt to deprive others of theirs or impede their efforts to obtain it. Each is the proper guardian of his own health, whether bodily or mental or spiritual. Mankind are greater gainers by suffering each other to live as seems good to themselves, than by compelling each to live as seems good to the rest.
From our philosophy book:
Although Mill agreed that democracy is the best form of government, in his essay On Liberty he exposes certain dangers inherent in the democracies. Principally, he warned that it is entirely possible for the will of the majority to oppress minorities. In addition, democracies have a kind of tyranny of opinion, which is as dangerous as oppression. Even in a democracy, therefore, it is necessary to set up safeguards against the forces that would deny individual freedom. In this respect, Mill reflected Bentham’s desire for reform to eliminate clear social evils. His particular focus is on preserving liberty by setting limits to the actions of government.
Mill argued that “the sole end for which mankind are warranted, individually or collectively, in interfering with the liberty of action of any of their number is self-protection. That the only purpose for which power can be rightly exercised over any member of a civilized community, against his will, is to prevent harm to others.” ... Mill’s argument for liberty was, therefore, an argument for individualism. Let individuals pursue their happiness in their own way. Even in the realm of ideas, we must be free to express our thoughts and beliefs, because truth is most quickly discovered when opportunity is given to refute falsehoods. Mill took the position that “there is the greatest difference between presuming an opinion to be true because, with every opportunity for contesting it, it has not been refuted, and assuming its truth for the purpose of not permitting its refutation.” He assumed, however, that it is important that the truth be known.