In medio stat virtus.
Virtue lies in the middle.
The truth lies somewhere in between.
Moderation is key.
Balance is the key to everything.
The concept of limit, of the right measure, in Plato.
Wikipedia:
The expression goes back to the medieval scholastic philosophers, although already Aristotle in the Nicomachean Ethics (”Μέσον τε καὶ ἄριστον” – The mean is the best thing), Horace in the Satires (“Est modus in rebus” – There is a measure in things), and Ovid in the Metamorphoses (“Medio tutissimus ibis – by following the middle way, you will walk most safely) had expressed a similar concept.
A comparable idea is also found in Buddhism: The path that leads to the cessation of suffering is called the Middle Way, because it avoids the two extremes of self-indulgence and self-mortification, excessive behaviors that do not lead to mental peace. This path, developed in the Noble Eightfold Path, consists in cultivating virtue, meditative serenity, and wisdom.