The clever trap Plato sets here lies in collapsing the usual complaint that anger is simply "irrational"—it's not that anger is wrong in general, but that it's misdirected energy, wasted on precisely the situations where it cannot accomplish anything. Most people understand this intellectually yet still simmer over traffic delays or a friend's thoughtless comment; the quote's real instruction is that anger requires us to make a sharp distinction between what we control and what we don't, then to recognize we're squandering our fury either way. When you catch yourself furious at a colleague's mistake (something they could have prevented), Plato's insight cuts deeper than "don't be angry"—it asks whether that anger is actually moving you toward a solution or merely making you feel justified in your frustration.