Jacob's ladder and his night of wrestling, Hagar in the desert, the strangers at Abraham's tent, Balaam's blocked road.
Before the New Testament, angels appear as strangers who turn out not to be strangers: the three visitors to Abraham, the hand that stops the knife at Isaac's throat, the ladder in Jacob's dream, the figure Jacob wrestles all night. Painters kept these encounters ambiguous on purpose — the wings often arrive late in the picture's logic, after you have already read the figure as a man.

Eugene Delacroix