Didoni marito opus erat;
Dido had need of a husband.
Æneæ c[oe]nâ usus erat;
Æneas had need of a dinner.
But opus appears to be sometimes placed like an adjective for
necessarius, necessary, as
Regi Anthropophagorum coquus opus est:
The King of the Cannibal Islands wants a cook.
Which would serve his purpose best-- a valet-de-chambre who _dresses_
men, or a wit, who _roasts_ them?