Russell's paradox

Lost innocence 

Once there was a time in which Mathematics was an innocent subject. In order to produce a mathematical system, all you had to do was develop some concepts, add some operations on these concepts (a calculus) and top it off with a few self-evident axioms. Euclid was the first to do this systematically.

Mathematics develops like anything else, as a resonating set of interrelated quanta, which are entangled with all things that are shaped by it.