I’ve always hated the quote about the definition of insanity being doing the same thing over and over again while expecting different results—first of all because it’s one of the most salient examples of my pet peeve of quote misattribution (Einstein never said it; try a mystery novelist who writes about cats), and secondly because “insanity” is clearly not the right word. Maybe the original quote was “inanity,” as in “absurdity,” although I would posit “stubborn” or “hidebound” even “obstinate to the point of idiocy” are better (and less offensive) terms.
But it’s also a frustrating quote because it pops into my mind, unbidden, every time I am attempting something and failing, specifically something I cannot get out of doing, like making these awful German Christmas cookies my dad loves.