_b._ Promissory Notes. These differ from Book accounts in that they are always either expressly or virtually on interest, and are consequently negotiable. They are issued by individuals, corporations, and Nations. If the principal be deemed secure, that is, if there be a thorough trust on the part of the holder in the maker of the note, the time of the payment of the principal becomes a matter of comparative indifference, because the interest is compensation for delay, and is often the motive on the part of the holder for rendering that service of which the note is evidence. Indeed a long obligation, other things being equal, is commonly preferred to a short one, and bears a higher price. When a note is sold (negotiated) by the original holder it becomes payable to the purchaser, or to each subsequent purchaser in turn, and thus may run a devious round, may play a part in many commercial transactions, may be set off by the transient holder against a debt owed by him and thus cancel that, and when itself is cancelled by ultimate set-off or by any other mode of payment the last holder takes the return for the service originally rendered by the first holder. The promissory notes of individuals are frequently discounted by Banks in a manner to be presently explained. These are always for short times, and are debts bought by banks on the personal security of the names upon the notes. The notes are founded on the relation of debtor and creditor, which is always a personal relation, and so differ in their nature from a _mortgage_, which is a qualified _title_ to a specific piece of property, usually real estate. A note secured by a mortgage is, as it were, absorbed into the mortgage, and becomes another thing from a common promissory note, or _commercial paper_, as it is called. A mortgage rests therefore on other grounds than a commercial trust in the good faith of a _person_.