“The acts of the mind, wherein it exerts its power over simple ideas, are chiefly these three: 1. Combining several simple ideas into one compound one, and thus all complex ideas are made. 2. The second is bringing two ideas, whether simple or complex, together, and setting them by one another so as to take a view of them at once, without uniting them into one, by which it gets all its ideas of relations. 3. The third is separating them from all other ideas that accompany them in their real existence: this is called abstraction, and thus all its general ideas are made.”

“[M]an's power, and its way of operation, [is] muchwhat the same in the material and intellectual world. For the materials in both being such as he has no power over, either to make or destroy, all that man can do, is either to unite them together, or to set them by one another, or wholly separate them.”

“I pretend not to teach, but to inquire; and therefore cannot but confess here again,–that external and internal sensation are the only passages I can find of knowledge to the understanding. These alone, as far as I can discover, are the windows by which light is let into this DARK ROOM. For, methinks, the understanding is not much unlike a closet wholly shut from light, with only some little openings left, to let in external visible resemblances, or ideas of things without: which, would they but stay there, and lie so orderly as to be found upon occasion, it would very much resemble the understanding of a man, in reference to all objects of sight, and the ideas of them.”

“Reverie is when ideas float in our mind without reflection or regard of the understanding.”

“One entered the world, Denis pursued, having ready-made ideas about everything. One had a philosophy and tried to make life fit into it. One should have lived first and then made one's philosophy to fit life...Life, facts, things were horribly complicated; ideas, even the most difficult of them, deceptively simple. In the world of ideas, everything was clear; in life all was obscure, embroiled. Was it surprising that one was miserable, horribly unhappy?”

“Every revolutionary idea seems to evoke three stages of reaction. They may be summed up by the phrases: (1) It's completely impossible. (2) It's possible, but it's not worth doing. (3) I said it was a good idea all along.”

“If you happen to read fairy tales, you will observe that one idea runs from one end of them to the other--the idea that peace and happiness can only exist on some condition. This idea, which is the core of ethics, is the core of the nursery-tales.”