where did the idiom speak of the devil come from
Speak of the devil Deriving from the Middle Ages, this proverb (which was, and to a certain extent still is, rendered as "Talk of the Devil...") was a superstitious prohibition against speaking directly of the Devil or of evil in general, which was considered to incite that party to appear, generally with unfortunate consequences. Its first printed usage in modern English can be found in Giovanni Torriano's Piazza Universale (1666), as "The English say, Talk of the Devil, and he's presently at your elbow."