More glossary items: a correction

[John Benson]

Actual etymology of "the calculus":

Long before the advent of the differential and integral calculus, there was
the renal calculus, known to moderns as the humble kidney stone. Ever since
Newton and Leibnitz, passing advanced mathematics has been considered as
hard as passing kidney stones, and much beer has been spilled in the attempt
to make both go more easily. As Latin was the lingua franca* of science
until the 1800's, it was natural for the gouty and kidney-stone-plagued
privileged classes attending college to refer to the agony of higher
mathematics first as a renal calculus, and later as "the" calculus.

As for the argument that the ancient Romans did arithmetic with stones,
lining them up to make I's, V's, X's and so on, I find it somewhat contrived
and much less satisfying than my theory: it's mine, and I own it.

* Latin for "language of the hot dogs" or "expert's language"