I cannot sufficiently admire the eminence of those men's wits, that have received and held it to be true, and with the sprightliness of their judgments offered such violence to their own senses, as that they have been able to prefer that which their reason dictated to them, to that which sensible experiments represented most manifestly to the contrary. ...I cannot find any bounds for my admiration, how that reason was able in Aristarchus and Copernicus, to commit such a rape on their senses, as in despite thereof to make herself mistress of their credulity.
All truths are easy to understand once they are discovered; the point is to discover them.
Truth is the daughter of time, not of authority.
It is not truth that makes man great, but man that makes truth great.
Do not go by revelation; Do not go by tradition; Do not go by hearsay; Do not go on the authority of sacred texts; Do not go on the grounds of pure logic; Do not go by a view that seems rational; Do not go by reflecting on mere appearances; Do not go along with a considered view because you agree with it; Do not go along on the grounds that the person is competent; Do not go along because "the recluse is our teacher." Kalamas, when you yourselves know: These things are unwholesome, these things are blameworthy; these things are censured by the wise; and when undertaken and observed, these things lead to harm and ill, abandon them... Kalamas, when you know for yourselves: These are wholesome; these things are not blameworthy; these things are praised by the wise; undertaken and observed, these things lead to benefit and happiness, having undertaken them, abide in them.