TITLE XXI. OF LITERAL OBLIGATION
Formerly there was a kind of obligation made by writing, and said to be contracted by the entry of a debt in a ledger; but such entries have nowadays gone out of use. Of course, if a man states in writing that he owes money which has never been paid over to him, he cannot be allowed, after a considerable interval, to defend himself by the plea that the money was not, in fact, advanced; for this is a point which has frequently been settled by imperial constitutions. The consequence is, that even at the present day a person who is estopped from this plea is bound by his written signature, which (even of course where there is no stipulation) is ground for a condiction. The length of time after which this defence could not be pleaded was formerly fixed by imperial constitutions at five years; but it has been reduced by our constitution, in order to save creditors from a more extended risk of being defrauded of their money, so that now it cannot be advanced after the lapse of two years from the date of the alleged payment.
TITLE XXII. OF OBLIGATION BY CONSENT
Obligations contracted by mere consent are exemplified by sale, hire, partnership and agency, which are called consensual contracts because no writing, nor the presence of the parties, nor any delivery is required to make the obligation actionable, but the consent of the parties is sufficient. Parties who are not present together, therefore, can form these contracts by letter, for instance, or by messenger: and they are in their nature bilateral, that is, both parties incur a reciprocal obligation to perform whatever is just and fair, whereas verbal contracts are unilateral, one party being promisee, and the other alone promisor.
TITLE XXIII. OF PURCHASE AND SALE
The contract of purchase and sale is complete immediately the price is agreed upon, and even before the price or as much as any earnest is paid: for earnest is merely evidence of the completion of the contract. In respect of sales unattested by any written evidence this is a reasonable rule, and so far as they are concerned we have made no innovations. By one of our constitutions, however, we have enacted, that no sale effected by an agreement in writing shall be good or binding, unless that agreement is written by the contracting parties themselves, or, if written by some one else, is at least signed by them, or finally, if written by a notary, is duly drawn by him and executed by the parties. So long as any of these requirements is unsatisfied, there is room to retract, and either purchaser or vendor may withdraw from the agreement with impunity—provided, that is to say, that no earnest has been given. Where earnest has been given, and either party refuses to perform the contract, that party, whether the agreement be in writing or not, if purchaser forfeits what he has given, and if vendor is compelled to restore double of what he has received, even though there has been no express agreement in the matter of earnest.
1 It is necessary that the price should be settled, for without a price there can be no purchase and sale, and it ought to be a fixed and certain price. For instance, where the parties agreed that the thing should be sold at a price to be subsequently fixed by Titius, the older jurists doubted much whether this was a valid contract of sale or not. The doubt has been settled in the following way by our decision; if the third person named actually fixes the price, it must certainly be paid, as settled by him, and the thing must be delivered, in order to give effect to the sale; the purchaser (if not fairly treated) suing by the action on purchase, and the vendor by the action on sale. But if the third person named will not or cannot fix the price, the sale will be void, because no price has been settled. This rule, which we have adopted with regard to sales, may reasonably be extended also to contracts of hire.