That one sentence blew my mind. Until then I had relied almost entirely on the geometric representation of a concept or a problem, and never knew to reach for the the actual concept.
I think about 75% of people check out of math completely super early; of the 25% that remain, 75% of those never quite "get" that math is a separate thing from graphs and charts. The rest are usually successful scientists, engineers, and similarly technical folk. (I won't venture my opinion on the difference between mere number manipulators vs. actual prov-ers of mathematics, but I think it's probably a similar ratio)