Source identified1
“Patience is the finest and worthiest part of fortitude,—and the rarest, too.”
Ruskin separates patience from mere persistence: fortitude is not only continuing to act, but also bearing delay, frustration and incomplete results without losing steadiness.
Source note: The Ethics of the Dust, Lecture IV, Project Gutenberg #4701. Ruskin immediately contrasts many persevering people with the rarer patient person and later insists that genuine patience is not necessarily passive or idle.