[ Etymonline :]
early 14c., "quality of being equal or fair, impartiality in dealing with others," from Old French equite (13c.),
from Latin aequitatem (nominative aequitas) "equality, uniformity, conformity, symmetry; fairness, equal rights; kindness, moderation,"
from aequus "even, just, equal" (see equal (adj.)).
As the name of a system of law, 1590s, from Roman naturalis aequitas, the general principles of justice which corrected or supplemented the legal codes.
Why was 'equity' was adopted to describe this Difference? Wouldn't 'remainder' or 'balance' fit more?
What explains this semantic specialization of meaning to accounting? What semantic notions underlie the emboldened abstract nouns overhead, with 'Assets — Liabilities'?