The spirit manifests itself by appearing and behaving as the summoned person in order to communicate the requested information.

A jury summons contains instructions that tell the summoned person how to report for jury duty.

In medieval Latin, praemunire was confused with and used for praemonere, to forewarn, as the writ commanded that the sheriff do (facias) warn (praemunire) the summoned person to appear before the Court.

The magician must somehow convey to the summoned person when he is meant to appear, otherwise (as Strange once observed) the summoned person might appear at any time and feel he had fulfilled his obligations.