If, in making a contract, it is taken for granted by both parties that a certain fact exists, the non-existence of which would make the contract impossible of performance, and the fact does not exist, the contract is void. The reason for this rule has been variously stated. By Professor Harriman it is said that the existence of the fact is a condition precedent to the formation of the contract;1 by Professor Langdell, that if the fact upon which the promise depends does not exist there is no promise at all.2 Perhaps it is best to say that, while there is an agreement, the law, in the interest of justice, attaches no obligation.
The existence of a fact may be said to be taken for granted by both parties only when neither party assumes the risk of its non-existence. Where one party undertakes that the fact exists, he assumes the risk, and though its non-existence may give to the other party the right to rescind the contract, it will not make the contract void. Thus, in the case of a sale of a cargo supposed to be on board a certain vessel, if the seller engages that there is a cargo, the non-existence of a cargo will relieve the buyer from the obligation to pay the price, or, if the price is paid, will give the buyer the right to rescind the contract and recover the price, but it will not relieve the seller from his engagement;1 if the seller does not undertake that there is a cargo, the existence of the cargo may be said to be taken for granted by both parties, and if, in fact, there is no cargo, the contract is void.2
1 Harriman, "Contracts," Sec. Sec. 305, 306.
2 Langdell, " Summary of the Law of Contracts," Sec. 28.