his own master, would so act. Such is the mode of thinking in
the classical period of the Roman law and it is closely paralleled by
an independent development of juristic thought in the rise of equity
and the absorption of the law merchant in our law.

It was easy to fit the two categories, delict and formal undertaking,
which had come down from the strict law, into the new mode of thought.
The typical delict required _dolus_--intentional aggression upon the
personality or the substance of another. Indeed Aquilian _culpa_, in
which the fault did not extend to intentional aggression, is a
juristic equitable development. Hence when the legal was identified
with the moral, and such identification is a prime characteristic of
this stage, the significant thing in delict seemed to be the moral
duty to repair an injury caused by wilful aggression. The legal
precept was _alienum non laedere_. Also the duty to perform an
intentional undertaking seemed to rest on the inherent moral quality
of a promise that made it intrinsically binding on an upright man. The
legal precept was _suum cuique tribuere_. Thus liability seemed to
flow from intentional action--whether in the form of aggression or in
the form of agreement. The "natural" sources of liability were delict
and contract. Everything else was assimilated to one or the other of
them. Liability without fault was quasi-delictal. Liability imposed by
good faith to prevent unjust enrichment was quasi-contractual. The
central idea had become one of the demands of good faith in view of
intentional action.

In the nineteenth century the conception of liability as resting on
intention was put in metaphysical rather than ethical form. Law was
a realization of the idea of liberty, and existed to bring about the
widest possible individual liberty. Liberty was the free will in
action. Hence it was the business of the legal order to give the
widest effect to the declared will and to impose no duties except in
order to effectuate the will or to reconcile the will of one with the
will of others by a universal law. What had been a positive, creative
theory of developing liability on the basis of intention, became a
negative, restraining, one might say pruning, theory of no liability
except on the basis of intention. Liability could flow only from
culpable conduct or from assumed duties. The abstract individual will
was the central point in the theory of liability. If one was not
actually cul