If a man of sense buys a work in a dozen volumes, and finds that only half a dozen pages are worth reading, he does well to cut out the half dozen pages and fling the rest into the fire.

Finally, it would be no unbecoming device for every great library to have inscribed over its portal, The Bedlam of the Human Mind.

At this point one might perhaps suggest to D'Alembert that study of the pathology of the mind is no bad means of surprising the secrets of humanity and life.
For his hour, however, the need was not knowledge of the thoughts, dreams, and mental methods of the past, but better mastery of the aids and instruments of active life.

In any case Diderot was right when he expressed his preference for the essay over the treatise: "an essay where the writer throws me one or two ideas of genius, almost isolated, rather than a treatise where the precious gems are stifled beneath a mass of iteration....

A man had only one idea; the idea demanded no more than a phrase; this phrase, full of marrow and meaning, would have been seized with relish; washed out in a deluge of words, it wearies and disgusts."[169] Rousseau himself does not surpass Diderot or D'Alembert in contempt for mere bookishness.