Most of the time, we latch onto specific symbols from the book in question—a certain white whale, a certain colorful capital letter—and grapple with what they mean right here.
But Campbell kind of defies "most of the time."
This dude has some very specific thoughts on symbols…which, ironically, makes it impossible to analyze any one specifically. In fact, Campbell was a little leery of doing so, since he thought people shouldn't get tripped up in the symbols themselves.
God and the gods are only convenient means—themselves of the nature of the world of names and forms, though eloquent of, and ultimately conducive to, the ineffable. They are mere symbols to move and awaken the mind, and to call it past themselves. (239.2)
In that sense, The Hero with a Thousand Faces covers every symbol ever put in a piece of fiction (phew, we're exhausted just thinking about it), and counting all of them would be like counting grains of sand at the beach. There's just no point.
That said, there are still a couple of places where he talks about symbols and meaning in a more concrete—if very, very general—sense. Click through to see our take on some of the biggies.