Back when I was in Uni I flunked Calculus II. The following year I switched Uni and - somewhat fortunately - I re-followed the same class. I say fortunately be

Back when I was in Uni I flunked Calculus II. The following year I switched Uni and - somewhat fortunately - I re-followed the same class. I say fortunately because during my first round at Calculus II I couldn't fathom the slightest underlying motivation for all the statements and proofs that were regurgitated during class. I had no bearing - I nearly panicked with the Cauchy Problem - and was doubting whether or not I was cut for Engineering at all. The following year the other Prof took a digression and for two weeks laid out Inf-dimentional spaces, Banach spaces, functionals, contractions, fixed points and so on. Then one morning, over the course of 2 hours he plugs in differential equations, the Cauchy problem and deals with it with such elegance, clarity and insight that I can still recollect the broad strokes. I had first hand proof of the blessing and the curse of mathematics...