"Pissing in a violin"="talking in the empty" didn't really shed any light on the expression for me. I had figured it meant "pissing in the wind"="engaging in a futile endevor".

It cracks me up we are treated to "pissing in a violin" but "c'est en faisant des erreurs qu'on apprend" is far too arcane an expression to translate... "It is in making errors that we learn" is not quite the leap that is "pissing in a violin" I would hazard.

Does "pissing" earn a profanity advisory?