Giving a thing, an animal or an abstract idea actions, feelings or speech that belong to a person.
In the Aeneid
Look for it, then, with your eyes raised high, and once you find it as you should, take it in your hand: it will come to you willingly and without cost, if the fates are calling you; otherwise, by no force will you conquer it, nor tear it away with hard iron.
The Sibyl says that the bough “will come willingly,” as if it chose whoever picks it. Giving the plant a will makes the gold a living test: it yields to the chosen one and resists whoever tries to take it by force.