TRADE AND EXCHANGE
During the barbarian invasions, commerce, which had had its chief center in the Mediterranean region, declined to a low ebb. Only in the east Mediterranean and in cities enjoying the protection of the Church did trade flourish. A number of conditions were necessary for the recovery and expansion of commerce which took place: (1) re-establishment of more peaceable conditions; (2) development of specialized industry; (3) growth of a money economy; (4) development of market organizations; (5) establishment of standards of conduct for carrying on exchange; and (6) improvement in transportation facilities. These developments are brought out in the documents of Parts II and III.
Not only the volume of trade, but also the knowledge of how to carry on exchange or transactions suffered greatly during the period of the barbarian invasions. In Section I, the various documents give some idea of the state of exchange in different parts of Europe from A.D. 500 to A.D. 1250. That there was a development in the ethics and technique of exchange is apparent. It does not follow, however, that the ethics, laws, and instruments of exchange had by the thirteenth century reached a higher state of perfection than that attained by the Romans as indicated in Justinian's Institutes.
The Institutes of Justinian ( A.D. 533), a summary of the principles of Roman jurisprudence, contains among other things legal definitions of buying and selling, barter, and pure and conditional contracts. These definitions may be interpreted as indicating the degree of perfection that exchange had reached by the time of the Caesars. They also in-