ssary to trespass a little on a subject which lies properly
beyond the range of these pages, the analysis of Agreement effected by
the Roman jurisconsults. Of this analysis, the most beautiful monument
of their sagacity, I need not say more than that it is based on the
theoretical separation of the Obligation from the Convention or Pact.
Bentham and Mr. Austin have laid down that the "two main essentials of
a contract are these: first, a signification by the promising party of
his _intention_ to do the acts or to observe the forbearances which he
promises to do or to observe. Secondly, a signification by the
promisee that he _expects_ the promising party will fulfil the
proffered promise." This is virtually identical with the doctrine of
the Roman lawyers, but then, in their view, the result of these
"significations" was not a Contract, but a Convention or Pact. A Pact
was the utmost product of the engagements of individuals agreeing
among themselves, and it distinctly fell short of a Contract. Whether
it ultimately became a Contract depended on the question whether the
law annexed an Obligation to it. A Contract was a Pact (or Convention)
_plus_ an Obligation. So long as the Pact remained unclothed with the
Obligation, it was called _nude_ or _naked_.

What was an Obligation? It is defined by the Roman lawyers as "Juris
vinculum, quo necessitate adstringimur alicujus solvendae rei." This
definition connects the Obligation with the Nexum through the common
metaphor on which they are founded, and shows us with much clearness
the pedigree of a peculiar conception. The Obligation is the "bond" or
"chain" with which the law joins together persons or groups of
persons, in consequence of certain voluntary acts. The acts which have
the effect of attracting an Obligation are chiefly those classed under
the heads of Contract and Delict, of Agreement and Wrong; but a
variety of other acts have a similar consequence which are not capable
of being comprised in an exact classification. It is to be remarked,
however, that the act does not draw to itself the Obligation in
consequence of any moral necessity; it is the law which annexes it in
the plenitude of its power, a point the more necessary to be noted,
because a different doctrine has sometimes been propounded by modern
interpreters of the Civil Law who had moral or metaphysical theories
of their own to support. The image of a _vinculum juris_ colours and
pervades every part of t