There are only four kinds of readers. The first is like the hour-glass; their reading being as the sand, it runs in and it runs out, and leaves no vestige behind. The second is like the sponge, which imbibes everything, and returns it in nearly the same state, only a little dirtier. A third is like a jelly-bag, allowing all that is pure to pass away, retaining only the refuse and dregs. And the fourth is like the slaves in the diamond mines, who, casting aside all that is worthless, retain only gems.
From the writings of English poet Samuel Taylor Coleridge (1772-1834)