Why does Dunstan choose history as his area of study? Does history teach him what he wants to know?

Dunstan is obsessed with mythology and saints: the study of history happens to be full of both of these,

As I have grown older my bias—the oddly recurrent themes of history, which are also the themes of myth—has asserted itself, and why not? But when I first stepped into a Colborne classroom, wearing the gown that we were all expected to wear then, I never thought that it would be more than forty years before I left it for good.