Ever notice how advanced math is just a towering skyscraper of complexity balanced on one tiny, precarious assumption? That's "the usual metric" - the mathematical equivalent of saying "trust me, bro" before building an entire theoretical universe. Mathematicians spend decades mastering calculus, real analysis, and measure theory, constructing elaborate intellectual castles, all while hoping nobody kicks that one foundational assumption they casually labeled "the usual metric." It's like spending years building the world's most sophisticated house of cards on a subway platform during rush hour.