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.]

Contracts perfected by consent--_consenses_--had reference to sale,
hiring, partnership, and mandate. All contracts of sale were good
without writing. When an article was sold and delivered, the market
price, as fixed by custom, determined the price, if nothing had been
said about it. The seller was bound to warrant that the thing sold was
free from defects, and when the subject did not answer this implied
warranty, the sale might be set aside. But the seller could stipulate