If we have no heretics we must invent them, for heresy is essential to health and growth.
Where two principles really do meet which cannot be reconciled with one another, then each man declares the other a fool and a heretic
The world is kept alive only by heretics: the heretic Christ, the heretic Copernicus, the heretic Tolstoy. Our symbol of faith is heresy. (Tomorrow)
All the heroes of tomorrow are the heretics of today.