who coined the phrase 'coin a phrase'?

Something that I have been wondering lately. I can’t see any logical connection between coins and phrases or sayings, so who came up with this expression?

tr.v. coined, coin·ing, coins
To make (pieces of money) from metal; mint or strike: coined silver dollars.
To make pieces of money from (metal): coin gold.
To devise (a new word or phrase).

I realise that def.3 is not helpful, but to coin is to create currency; that currency need not be tangible.

It’s similar, I suppose, to say that X laid the foundation for Y, where X and Y are concepts, not tangible structures.

First Google hit on “coin a phrase” origin:

http://www.wordorigins.org/wordorc.htm

Second Google hit on “coin a phrase” origin:

http://www.takeourword.com/TOW150/page2.html