And indeed nothing but the most determined scepticism, along with a great degree of indolence, can justify this aversion to metaphysics. For if truth be at all within the reach of human capacity, it is certain it must lie very deep and abstruse: and to hope we shall arrive at it without pains, while the greatest geniuses have failed with the utmost pains, must certainly be esteemed sufficiently vain and presumptuous. I pretend to no such advantage in the philosophy I am going to unfold, and would esteem it a strong presumption against it, were it so very easy and obvious.

Nothing is more dangerous to reason than the flights of the imagination and nothing has been the occasion of more mistakes among philosophers.

Nothing is demonstrable, unless the contrary implies a contradiction. Nothing, that is distinctly conceivable, implies a contradiction. Whatever we conceive as existent, we can also conceive as non-existent. There is no being, therefore, whose non-existence implies a contradiction. Consequently there is no being, whose existence is demonstrable.

When men are most sure and arrogant they are commonly most mistaken, giving views to passion without that proper deliberation which alone can secure them from the grossest absurdities.

If the religious spirit be ever mentioned in any historical narration, we are sure to meet afterwards with a detail of the miseries which attend it. And no period of time can be happier or more prosperous, than those in which it is never regarded or heard of.

The whole of natural theologyresolves itself into one simple, though somewhat ambiguous proposition, That the cause or causesof order in the universe probably bear some remote analogy to human intelligence.

The greatest crimes have been found, in many instances, to be compatible with a superstitious piety and devotion; hence it is justly regarded as unsafe to draw any inference in favor of a man's morals, from the fervor or strictness of his religious exercises, even though he himself believe them sincere.