of the emperors Leo and
Zeno, which is inserted in the Justinian code, mentions the fleet which was
kept to guard the treasures: and by another law, taken from the Theodosian
code, we learn, that the guards of the treasures, who went in this fleet,
were officers under the superintendent of the imperial revenue.

3. We have already mentioned the dependence of Rome on foreign nations for
corn, and the encouragement given, during the republic and in the early
times of the empire, to the importation of this necessary article. In the
Theodosian and Justinian code, encouragement to the importation of it seems
still to have been a paramount object, especially from Egypt; for though
from an edict of Justinian it would appear that the cargoes from this
country, of whatever they consisted, were guarded and encouraged by law,
yet we know that the principal freight of the ships which traded between
Alexandria and Rome and Constantinople was corn, and that other merchandize
was taken on board the corn fleets only on particular occasions, or, where
it was necessary, to complete the cargoes. Among the other edicts of
Justinian, regulating the trade of Egypt, there is one which seems to have
been passed in consequence of the abuses that had crept into the trade of
corn and other commodities, which were shipped from Alexandria for
Constantinople. These abuses arose from the management of this trade being
in the hands of a very few persons: the emperor therefore passed a law,
dividing the management into different branches, each to be held by
separate individuals. From the code of Justinian we also learn, that corn
was embarked from other ports of Egypt besides Alexandria, by private
merchants; but these were not permitted to export it without permission of
the emperor, and even then not till after the imperial fleet was fairly at
sea. The importance of the corn trade of Egypt fully justified these laws;
for at this period Constantinople was annually supplied with 260,000
quarters of wheat from this country.

The resources of the Romans were principally derived from the tribute
levied on the conquered countries; but in part also from duties on
merchandize: in the latter point of view, alone, they fall under our
notice. No custom duties seem to have been imposed till the time of
Augustus; but in his reign, and that of his immediate successors, duties
were imposed on every kind of merchandize which was imported into Rome; the
rate varied f