He told me that facts gave birth to, and were the absolute ground of, principles; to which I said, that unless he had a principle of selection, he would not have taken notice of those facts upon which he grounded his principle. You must have a lantern in your hand to give light, otherwise all the materials in the world are useless, for you cannot find them; and if you could, you could not arrange them.
21 September 1830 - Table Talk (1821-1834)