I don't put too much stock in quotes. Too often they are nothing more than platitudes, misapplied and often misattributed. A perfect example of the latter is Einstein's "The definition of insanity is doing the same thing over and over and expecting a different result."
Number one, that is NOT the definition of insanity and, number two, Einstein never said it. That quote is from a book, written in the 1980s by Rita Mae Brown, titled Sudden Death.
Then we have the ever-popular and supremely trite "All politics is local." The next time anyone throws that one at you, ask for an actual, coherent explanation of its meaning (um, uh, and random stuttering do NOT go toward word count).
There are two quotes that particularly make my skin crawl though, mostly because, on a daily basis, I interact with the results of those quotes being taken to heart. They are "Perfection is the enemy of the good." and, "Done is better than good."
These two quotes attempt to legitimize the ideology of the incompetent, the belief of the bungler, the mantra of the mediocre. If you agree with either (or both), and have little to no mechanical comprehension and manual dexterity, combined with the know-it-all hubris of a teenager, perhaps a career in the gunsmithing field is for you.