CLICK HERE FOR KEY TO SOURCES
The phrase refers to the medieval practice of extorting money from the Jewish community on pain of the threatened torture of its leaders; such torture may or may not have involved blinding. Another version suggests that every organ carried a price, and that the ultimate was the eye, which would be gouged out were a wealthy Jew not to disgorge his fortune. (Jonathon Green)
From: Notes and Queries
A Medium of Intercommunication for Literary Men, General Readers, etc.
Sixth Series-Volume Ninth, January-June, 1884. P. 209