2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/123968Some personal thoughts and opinions on what ``good quality mathematics'' is, and whether one should try to define this term rigorously. As a case study, the story of Szemerédi's theorem is presented.12 pages, no figures. To appear, Bull. Amer. Math. SocHistory and Overview00A30text