[The Big Sky] owes much of its convincing authenticity not only to Guthrie's use of historical sources, but to the imaginative manner in which he wove the texture of his design to recreate a region which "is not oppressed," wrote the Reverend Samuel Parker, "by the tyranny of religion," nor "awed by the frown of virtue."

And this imaginative excellence in interpolating a vivid fiction from historical fact in turn owes much to Guthrie's own longstanding love affair with the American West, an affection reflected in every page of the book. Indeed, while writing the book he claims to have achieved a kind of mystical unity with the characters, an empathy which kept him writing ahead of his research. (p. 174)

Still, such empathy would doubtless be impossible if the West were not a sounding board for Guthrie's own philosophical reflections on the nature of man, time, and space...