Rights of parties to a contract made by agent not disclosed

If an agent makes a contract with a person who neither knows, nor has reason to suspect, that he is an agent, his principal may require the performance of the contract; but the other contracting party has, as against the principal, the same rights as he would have had as against the agent if the agent had been principal. If the principal discloses himself before the contract is completed, the other contracting party may refuse to fulfil the contract, if he can show that, if he had known who was the principal in the contract, or if he had known that the agent was not a principal, he would not have entered into the contract.