Who is Sheikh Darwish from Midaq Alley and what is their importance?

A man in his fifties, whose native cloak and wooden sandals contrast with Western-style necktie and expensive-looking gold-rimmed spectacles, the homeless Darwish spends most of his time in Kirsha's Café sitting stiff as a statue and silent as a corpse, lost in a world of his own. He rouses himself, occasionally speaks his philosophical piece, inevitably ending with an Arabic word, which he translates into English and spells—and then sinks back into reverie.