The same holds for mathematical truths. It’s questionable whether the statement “2 + 2 = 4” or “In Peano arithmetic, SS0 + SS0 = SSSS0″ can be said to be true in any purely abstract sense, apart from physical systems that seem to behave in ways similar to the Peano axioms.
Why is that important?
I practice historical European swordsmanship, and those Musashi quotes have a certain resonance to me*. Here is another (modern) saying common in my group:
If it’s stupid, but it works, then it ain’t stupid.
you previously asked why you couldn’t find similar quotes from European sources—I believe this is mainly a language barrier: The English were not nearly the swordsmen that the French, Italians, Spanish, and Germans were (though they were pretty mean with their fists). You should be able to find many quotes in those other languages.