When, and under what conditions, does one decide to press for change, to take on a new project, to embark on a journey, to develop a new theory, or to harness oneself to a cause? Can one know when to pursue a hunch and when to dismiss it? Can one know in advance when to engage and when to leave things be? No, in a sense one never does.
The kind of certainty one seeks in the proverb “God grant me the equanimity of accepting what cannot be changed, the courage to change what can be changed, and the wisdom to distinguish between the two” does not really exist except in trivial cases. In matters of importance, one cannot know in advance what can be changed and what cannot be changed, what should be accepted and what should be rejected, no matter how wise and how knowledgeable one is.
— The Tale of a Scale by Solly Angel