The Curious Autodidact

Readers may be divided into four classes: 1. Sponges, who absorb all that they read and return it in nearly the same state, only a little dirtied. 2. Sand-glasses, who retain nothing and are content to get through a book for the sake of getting through the time. 3. Strain-bags, who retain merely the dregs of what they read. 4. Mogul diamonds, equally rare and valuable, who profit by what they read, and enable others to profit by it also.

–Samuel Taylor Coleridge, poet, critic (1772-1834)