"The only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others."

"The only source of improvement is liberty, combined with the power of individuals to think for themselves."

"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."

"The peculiar evil of silencing the expression of an opinion is, that it is robbing the human race."

"Originality is the only thing which cannot be produced by any process of imitation."