Though a seller who knows the illegal purposes of a buyer of goods of a character not exclusively appropriate for such purposes, may not on that account be denied a right to recover the price of the goods, he may, nevertheless, while the contract is still executory, refuse to carry it out. While the buyer's illegal purpose will not protect him against an action for the price, it will certainly deprive him of his cause of action against the seller if the latter was ignorant at the time the contract was made of the buyer's illegal purpose; 51 and even though the seller was then cognizant of the illegal purpose it seems that the result should be the same. The buyer is equally guilty in both cases, and it is his guilt which should determine whether he can recover.