Areopagitica
1.  A fugitive and cloistered virtue--one not tried--is not to be esteemed; goodness untested will fall.
2.  With Reason God gave man freedom; thus man must be allowed to choose.
3.  Sin cannot be banned by law.
4.  Faith and Knowledge grow by exercise; one can be a heretic in the truth.
5.  Truth and falsehood look much alike; thus we must be allowed to divide one from the other.  For this we need prudence, forbearance, and tolerance.
6.  Truth will win out over falsehood; she needs not the help of censors, who impose the “iron yoke of outward conformity.”