originally the same, a sum certain, promised in such wise as
to endanger the general security if the promise is not carried out. In
Roman law, the condiction, which is the type of actions _in personam_,
and thus the starting point historically of rights _in personam_ and
of theories of obligation, was at first a recovery of a thing certain
or a sum certain due upon a promise of this sort. In juristic terms,
the central idea of the beginnings of liability is duty to make
composition for or otherwise avert wrath arising from the affronted
dignity of some personality desirous of vengeance, whether an injured
individual, a god or a politically organized society. Greek law and
Roman law give the name of "insult" to legally cognizable injury to
personality. Insult to a neighbor by injury to him or to one of his
household, insult to the gods by impious breach of the promise they
had witnessed, insult to the people by wanton disregard of the
undertaking solemnly made in their presence, threatened the peace and
order of society and called for legal remedy.

Lawyers begin to generalize and to frame conscious theories in the
later part of the stage of the strict law. At first these theories are
analytical rather than philosophical. The attempt is to frame general
formulas by which the rigid rules of the strict law may be reconciled
where they overlap or conflict or may be distinguished in their
application where such overlapping or conflict threatens. By this
time, the crude beginnings of liability in a duty to compound for
insult or affront to man or gods or people, lest they be moved to
vengeance, has developed into liability to answer for injuries caused
by oneself or done by those persons or those things in one's power,
and liability for certain promises made in solemn form. Thus the basis
of liability has become twofold. It rests on the one hand upon duty to
repair injury. It rests on the other hand upon duty to carry out
formal undertakings. It is enough for this stage of legal development
that all cases of liability may be referred to these two types and
that useful distinctions may be reached therefrom. Consideration of
why one should be held to repair injury, and why he should be held to
formal undertakings, belongs to a later stage.

Juristic theory, beginning in the transition from the strict law to
the stage of equity or natural law, becomes a force in the latter
stage. As the relations with which the law must deal b