All that belongs to human understanding, in this deep ignorance and obscurity, is to be sceptical, or at least cautious, and not to admit of any hypothesis whatever, much less of any which is supported by no appearance of probability.

It affords a violent prejudice against almost every science, that no prudent man, however sure of his principles, dares prophesy concerning any event, or foretell the remote consequences of things.

A miracle is a violation of the laws of nature; and as a firm and unalterable experience has established these laws, the proof against a miracle, from the very nature of the fact, is as entire as any argument from experience can possibly be imagined.

Vanity is so closely allied to virtue, and to love the fame of laudable actions approaches so near the love of laudable actions for their own sake, that these passions are more capable of mixture than any other kinds of affection; and it is almost impossible to have the latter without some degree of the former.

Mohammed praises [instances of] tretchery, inhumanity, cruelty, revenge, and bigotry that are utterly incompatible with civilized society.

The fact that different cultures have different practices no more refutes [moral] objectivism than the fact that water flows in different directions in different places refutes the law of gravity

From causes which appear similar, we expect similar effects. This is the sum total of all our experimental conclusions.