The term credit has already several times been used and a credit transaction has been incidentally defined as denoting an uncompleted exchange. Since modern banking proceeds upon a money basis in the sense that the banker obligates himself to pay money on demand, the practical current definition to be given to credit should be that of exchange in which no money passes, or as a form of exchange which is conducted without the use of money. Objection may be made that this would admit barter transactions which in no sense are credit operations. If, for example, A exchanges skins for grain which has been raised by B, the transaction is closed when the exchange takes place, and no money has intervened. Narrowly speaking, therefore, primitive barter of this kind would be included within the definition of credit which has already been suggested. A means of further safeguarding the definition might be found by introducing the so-called time element and regarding credit transactions as those that are closed only after the lapse of a certain length of time. Indeed, many writers on the subject regard the time element as the essential or characteristic feature of credit. This does not seem to be a well-warranted view of the case. As will be seen at a later point, many transactions which result in an immediate closing of obligations contain no time limit, as, for example, when A purchases goods from B and pays B with a check on his bank. This, as will be seen in later pages, is unmistakably a credit transaction, yet it involves no postponement of settlement as between A and B. Recognizing the possible difficulties to which the definition is thus open, the idea of credit as a system of indirect exchange or exchange without money - hence, at any given moment uncompleted exchange - is accordingly adhered to.