Four Kinds of Readers

 

From Robert Richardson's biography of Emerson:

Coleridge notes that there are four kinds of readers: the hourglass, the sponge, the jelly bag, and the Golconda. In the first everything that runs in runs right out again.  The sponge gives out all it took in, only a little dirtier.  They jelly bag keeps only the refuse.  The Golconda runs everthing through a sieve and keeps only the diamonds.  

(Emerson, Richardson says, "was not a systematic reader, but he had a genius for skimming and a comprehensive system for taking notes.  Most of the the time he was the pure Golconda, what miners call a high-grader, working his way rapidly through vast mines of material and pocketing the richest bits.  He read rapidly, looking for what he could use.  Certain books, among them Plutarch and Montaigne, were particularly rich for him and could bear endless rereading.

Wondering what a "Golconda" is?  Webster's online is helpful on this:

In the 16th century, Golconda was the capital of the Qutb Shahi kingdom in southern India, near modern Hyderabad. The city was home to one of the most powerful Muslim sultanates in the region and was the center of a flourishing diamond trade. Magnificent diamonds were taken from the mines in the hills surrounding Golconda, including Darya-e Nur (meaning "sea of light"), at 185 carats, the largest and finest diamond of the crown jewels of Iran. By the 1880s, "Golconda" was being used generically by English speakers to refer to any particularly rich mine, and later to any source of great wealth.

Golconda is also the name of a painting by Rene Magritte in 1953.  Renemagritte.org explains the title:

As was often the case with Magritte's works, the title Golconda was found by his poet friend Louis Scutenaire. Golconda is a ruined city in the state of Andhra Pradesh, India, near Hyderabad, which from the mid-14th century until the end of the 17th was the capital of two successive kingdoms; the fame it acquired through being the center of the region's legendary diamond industry was such that its name remains, according to the Oxford English Dictionary, "a synonym for 'mine of wealth'."