Alberto Corelli offers to pay $2,500 to purchase a painting titled Moonrise from Tara Shelley, an artist whose works have been causing a stir in the art world. Shelley accepts Corelli's offer. Assuming that the contract has met all of the requirements for a valid contract, answer the following questions.

Both parties are adults, and the contract, which is in writing, states that Corelli will pay Shelley the $2,500 the following day. In the meantime, Shelley allows Corelli to take the painting home with him. The next day, Corelli's son returns the painting to Shelley, stating that he is canceling the contract. He explains that his father has been behaving strangely lately, that he seems to be mentally incompetent at times, and that he clearly was not acting rationally when he bought the painting, which he could not afford. Is the contract enforceable? Discuss fully.