At Rome, pledges were customary, as a security for money due, on condition of their restoration after the payment of a debt. Real property, like houses and lands, as well as movables, were the subject of pledge. [Footnote: D. 20, 1.] The creditor was bound to bestow ordinary care and diligence in the preservation of the subject, but he could not use it, or take the profits of it, without a special contract. By the _pactum antichresis_, the creditor was allowed to take the profits in lieu of the interest on his debt; by the _lex commissoria_, the thing pledged became the absolute property of the creditor if the debt was not paid at the time agreed on. But as this condition was found to be a source of oppression, it was prohibited by a law of Constantine. [Footnote: C, 7, 35.] When the debt, interest, and all necessary expenses were paid, the debtor was entitled to have his pledge restored to him. After the time of payment was passed, the creditor had a right to sell the pledge, and retain his debt out of the produce of the sale; if there was a deficiency, the balance could be recovered by an action; if there was a surplus, the debtor was entitled to it. The Roman pledge was of the nature of the modern business of pawnbroking and of a mortgage. [Sidenote: Verbal Contracts.] Next to the perfection of contracts by the intervention of things _re_, were obligations contracted by _verbis_--solemn words-- and by _literis_ or writing. The _verborum obligatio_ was contracted by uttering certain formal words of style, an interrogation being put by one party and an answer given by the other. These stipulations were binding. In England all guarantees must be in writing. [Sidenote: Written obligations.] The _obligatio literis_ was a written acknowledgment of debt chiefly employed when money was borrowed, but the creditor could not sue upon the note within two years from its date, without being called upon also to prove that the money was in fact paid to the debtor. [Sidenote: Sales.]