Except when when the great change requires a leap of understanding. Regardless of how diligently she works, the person who is blind in a particular area will never make the necessary transcendental leap that creates new understanding.

I have experienced this, working in a room full of brilliant people for a period of months. It took the transcendental leap of understanding by someone outside the group to present the elegantly-simple solution to the apparently intractable problem.

So, while many problems will fall to persistence and diligence, some problems require at least momentary transcendental brilliance ... or at least a favorable error. Hmm, this says something about the need for experimentation as well. Never underestimate the power of, "Huh, that's funny. It's not supposed to do that ..."

Brian