Every theory in philosophy, which is built on pure conjecture, is an elephant; and every theory that is supported partly by fact, and partly by conjecture, is like Nebuchadnezzar's image, whose feet were partly of iron, and partly of clay.

[I]f a man bred to the seafaring life, and accustomed to think and talk only of matters relating to navigation, enters into discourse upon any other subject; it is well known, that the language and the notions proper to his own profession are infused into every subject, and all things are measured by the rules of navigation: and if he should take it into his head to philosophize concerning the faculties of the mind, it cannot be doubted, but he would draw his notions from the fabric of the ship, and would find in the mind, sails, masts, rudder, and compass.

In every case, we ought to act that part towards another, which we would judge to be right in him to act toward us, if we were in his circumstances and he in ours; or more generally - What we approve in others, that we ought to practise in like circumstances, what we condemn in others we ought not to do.

The laws of nature are the rules according to which the effects are produced; but there must be a cause which operates according to these rules. The laws of navigation never navigated a ship. The rules of architecture never built a house.

A philosopher is, no doubt, entitled to examine even those distinctions that are to be found in the structure of all languages... in that case, such a distinction may be imputed to a vulgar error, which ought to be corrected in philosophy.

In every chain of reasoning, the evidence of the last conclusion can be no greater than that of the weakest link of the chain, whatever may be the strength of the rest.

The rules of navigation never navigated a ship. The rules of architecture never built a house.