Full Idea
It is unsurprising that geometry was discovered in the necessity of Nile land measurement, since everything in the world of generation goes from imperfection to perfection. They would naturally pass from sense-perception to calculation, and so to reason.
Gist of Idea
The origin of geometry started in sensation, then moved to calculation, and then to reason
Source
Proclus (Commentary on Euclid's 'Elements' [c.452]), quoted by Charles Chihara - A Structural Account of Mathematics 9.12 n55
Book Reference
Chihara,Charles: 'A Structural Account of Mathematics' [OUP 2004], p.282
A Reaction
The last sentence is the core of my view on abstraction, that it proceeds by moving through levels of abstraction, approaching more and more general truths.