Mary sees a horse running in Troy's fields and decides to see if Troy will sell her the horse. During the course of negotiations, Troy realizes that Mary is confused about the name of the horse she wants$-$she keeps using the name Misty, who is actually an old not in good shape horse, when the horse she saw in the field is named Sissy. Troy draws up a written contract in which he agrees to sell Misty to Mary for $$3000$ and they both sign it$.$ When Mary brings a trailer to pick up her horse, she realizes that she has bought the wrong horse and refuses to pay for Misty. Troy sues Mary for breach of contract.

Question: How should the judge rule?