What are the motifs in The Viceroy of Ouidah by Bruce Chatwin?

The Heart of Darkness is a strong idea that resonates through the book. A blurb on this book's back cover equates it to Joseph Conrad's famous novel, The Heart of Darkness. This is a fair comparison, because a key theme of The Viceroy of Ouidah concerns the very substance of the heart of darkness. Rather than the darkness of night per se, the book deals with spiritual darkness and the lack of enlightenment that results from ignorance.