What does the idiom in this text suggest?
"Speak of the devil!" Reagan declared when Elijah strolled into the room.

 - Reagan had just been speaking about Elijah.
 - Reagan didn't trust Elijah.
The text uses an idiom, an expression that cannot be understood literally.
The idiom speak of the devil suggests that Reagan had just been speaking about Elijah. People say this when the person they've just been speaking about coincidentally arrives, as if summoned.