the.com/golden mean

means The desirable middle ground between two extremes of excess and deficiency, especially in character or conduct — courage, say, sitting between recklessness and cowardice.

from Rooted in ancient Greek philosophy, especially Aristotle's doctrine of the mean in the 'Nicomachean Ethics,' where virtue is found as a midpoint between vices of excess and deficiency. The 'golden' part comes later, from Latin 'aurea mediocritas' ('golden middle way'), a phrase from the Roman poet Horace, who prized moderation as a kind of quiet richness — not dullness, but something prized like gold.