... if you insist that the inference is made by a chain of reasoning, I desire you to produce that reasoning. The connection between the two is not intuitive. There is required a medium, which may enable the mind to draw such an inference, if indeed it be drawn by reasoning and argument. What that medium is, I must confess, passes my comprehension; and it is incumbent on those to produce it, who assert that it really exists, and is the origin of all our conclusions concerning matter of fact.

..all arguments concerning existence are founded on the relation of cause and effect; that our knowledge of that relation is derived entirely from experience; and all our experimental conclusions proceed upon the supposition that the future will be conformable to the past. .... Without the influence of custom, we should be entirely ignorant of every matter of fact beyond what is immediately present to the memory and senses.

To hate, to love, to think, to feel, to see; all this is nothing but to perceive.

The difference between a man who is led by opinion or emotion and one who is led by reason. The former, whether he will or not, performs things of which he is entirely ignorant; the latter is subordinate to no one, and only does those things which he knows to be of primary importance in his life, and which on that account he desires the most; and therefore I call the former a slave, but the latter free.

Mankind are so much the same, in all times and places, that history informs us of nothing new or strange in this particular. Its chief use is only to discover the constant and universal principles of human nature.

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

It is not reason which is the guide of life, but custom.