Does the phrase "stable author" mean an author who is not unstable, or a member of the agent's stable?
(I'm pretty sure it just means a trusted author/one that's been signed. I'm just wondering about the origin of the phrase)
I don't know the actual origin of the phrase, but it does not refer to the fact that the author is stable, mentally or in terms of output. It prefers to the fact that they are part of the "stable" of reliable earners on the client list. To be perfectly honest, I think "stable" is supposed to invoke the idea of ... a place where you keep horses.
....Yeah, I'm kind of grossed out, too.