A man posing for a painting.

It is more rational to suspect knavery and folly than to discount, at a stroke, everything that past experience has taught me about the way things actually work

Do you come to a philosopher as to a cunning man, to learn something by magic or witchcraft, beyond what can be known by common prudence and discretion?

There has been a controversy started of late, much better worth examination, concerning the general foundation of Morals; whether they be derived from Reason, or from Sentiment; whether we attain the knowledge of them by a chain of argument and induction, or by an immediate feeling and finer internal sense; whether, like all sound judgement of truth and falsehood, they should be the same to every rational intelligent being; or whether, like the perception of beauty and deformity, they be founded entirely on the particular fabric and constitution of the human species.

Reason, in a strict sense, as meaning the judgment of truth and falsehood, can never, of itself, be any motive to the will, and can have no influence but so far as it touches some passion or affection. Abstract relations of ideas are the object of curiosity, not of volition. And matters of fact, where they are neither good nor evil, where they neither excite desire nor aversion, are totally indifferent, and whether known or unknown, whether mistaken or rightly apprehended, cannot be regarded as any motive to action.

It seems certain, that though a man, in a flush of humour, after intense reflection on the many contradictions and imperfections of human reason, may entirely renounce all belief and opinion, it is impossible for him to persevere in this total scepticism, or make it appear in his conduct for a few hours.

Friendship is a calm and sedate affection, conducted by reason and cemented by habit; springing from long acquaintance and mutual obligations, without jealousies or fears, and without those feverish fits of heat and cold, which cause such an agreeable torment in the amorous passion.