David Reed wrote
>3) Newton's Principia also has qed exclusively.
After Proposition VII of book one, since it is a problem, Newton writes Q E I
for that which was to have been found.
After theorems, Euclid writes
hoper edei deiksai,
which Sir Ivor Bulmer Thomas translates
which was to be proved,
and I translate
the very thing it was necessary to show.
Best wishes from Annapolis,
Sam Kutler