"To be a philosophical sceptic is, in a man of letters, the first and most essential step towards being a true philosopher."

"All belief of matter of fact or real existence is derived merely from some object present to the memory or senses, and a customary conjunction betwixt that and some other object."

"The passion of love is a much more powerful principle of action than reason."

"The greater the object, the less it can be conceived by the imagination."

"It is not contrary to reason to prefer the destruction of the whole world to the scratching of my finger."