"the swine untethered in pairs rushing coupled into the sea"
The Swine Driven into the Sea
Public DomainThe Swine Driven into the Sea - Credit: James Tissot

In the Book of Matthew, when Jesus is crossing Gergesenes he is accosted by two men possessed by devils.

 

And, behold, they cried out, saying, What have we to do with thee, Jesus, thou Son of God? art thou come hither to torment us before the time? And there was a good way off from them an herd of many swine feeding. So the devils besought him, saying, If thou cast us out, suffer us to go away into the herd of swine. And he said unto them, Go. And when they were come out, they went into the herd of swine: and, behold, the whole herd of swine ran violently down a steep place into the sea, and perished in the waters. (Matthew 8.29-32)

 

Quentin’s fantasy of Caddy and Dalton Ames’ coupled bodies as those of the devil-possessed swine ties in with the imagery of page 125: “the beast with two backs and she blurred in the winking oars running the swine of Euboeleus running coupled within”. See note.