Posted by Bruce Kahl on June 11, 2001
In Reply to: "Beast of two backs" posted by Mgnat on June 11, 2001
: Also appears in opening pages of Rabelais' "Gargantua and Pantagruel." (c. 1530?)
Also in Othello, spoken by Iago. He was spreading lies about her sexual affairs.
The phrase is slang for sexual intercourse as when Iago said "..I am one, sir, that comes to tell you your daughter and the Moor are now making the beast with two backs" (1.1.116-117).
I saw somewhere that the 2 sexes were from a mythical beast with 2 backs and that only copulation could draw them asunder.