82 THE ROMAN EMPIRE
actions ( Digest 14.3.5.7, Labeo) and devising an action against a person
who authorized a representative to carry out a particular transaction ( Digest
14.3.19 pref; 19.1.13.25, Papinian).
Finally, the Principate saw no major developments in the Roman law of
banking. The only sign that lawyers were shifting their position to take
account of commercial realities is in the rather halting movements they
made toward recognizing deposit banking as a specifi c institution. Depositum
was traditionally gratuitous; the receiver held the object on trust and
returned it on demand. But texts of Antonine and Severan jurists recognize
an investment account at a bank as a category of depositum and admit the
payment of interest to the depositor ( Digest 16.3.28,24,26.11).
This brief investigation of some aspects of commercial law suggests that,
fi rst, Roman law was capable of making adjustments to rules that inhibited
the operation of business and trade, but was not prepared to sacrifi ce any
major principles; and secondly, that the more striking developments, such as
they were, did not take place in the period of the Principate, which was
rather a period in which earlier developments were absorbed, interpreted
and modestly extended. The legal authorities were not under great pressure
from the ‘commercial world’ to break established traditions of economic
behaviour. These conclusions are compatible with the hypothesis that trade
and commerce experienced modest but not startling growth under the
Principate.
Agriculture deserves special attention as the creator of the bulk of the
empire’s wealth. A case for progress in agriculture would centre on
developments in the West of the empire, such as the spread of vineyards in
Gaul, the extension of olive groves in north Africa and of wheat production
in north Gaul, south Britain and north Africa. New land was opened up, old
land converted to new use, and particularly in wet- farming areas, improved
techniques developed (in Gaul) or diffused (in Britain), notably in the labour-
intensive operations of harvesting and ploughing. Agricultural slavery was
introduced at least in pockets, creating the possibility of higher returns
through a more complete exploitation of the work force. Foreign investment
and immigration boosted the agrarian economy of the western provinces.
An additional stimulus – but also a crucial limiting factor – was provided
by the tax demands of the central government. The interests and needs of
the Roman government were few. Apart from war and diplomacy, its basic
concern was to supply and fi nance the military, bureaucracy and court.
Beyond feeding the plebs of the city of Rome, a standing obligation, the
government committed itself to expenditure on public buildings and
amenities for the capital city and the periodic furnishing of material aid to
communities in times of crisis. It was the tax on agricultural land in all the
provinces (but not Italy) which paid for the bulk of this expenditure. To the
extent that this constituted a new demand, or surpassed the impositions of
earlier authorities (Roman or pre-Roman), then the size of the surplus had
to be increased in order to meet it. In addition, some change of land use was