from
Bouvier's Law Dictionary, Revised 6th Ed (1856)
NATURAL EQUITY. That which is founded in natural justice, in honesty and
right, and which arises ex aequo et bono. It corresponds precisely with the
definition of justice or natural law, which is a constant and perpetual.
will to give to every man what is his. This kind of equity embraces so wide
a range, that human tribunals have never attempted to enforce it. Every code
of laws has left many matters of natural justice or equity wholly unprovided
for, from the difficulty of framing general rules to meet them, from the
almost impossibility of enforcing them, and from the doubtful nature of the
policy of attempting to give a legal sanction to duties of imperfect
obligation, such as charity, gratitude, or kindness. 4 Bouv. Inst. n. 3720.