E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
Virtually blind, but not wholly so, what the French call ber-lue; our par-blind. (Old English suffix sam, half; or Old High German sand, virtually.) It is only fit for a Launcelot Gobbo to derive it from sand, a sort of earth.
This is my true-begotten father, who, being more than sand-blind, high-gravel blind, knows me not.Shakespeare: Merchant of Venice, ii. 2.