Alexander the Oracle-monger (32)

This triple rogue now hit upon an idea which would have been too clever for the ordinary robber. Opening and reading the packets which reached him, whenever he came upon an equivocal, compromising question, he omitted to return the packet; the sender was to be under his thumb, bound to his service by the terrifying recollection of the question he had written down. You know the sort of things that wealthy and powerful personages would be likely to ask. This blackmail brought him in a good income.