The Stoics give us a marvelous concept: the Inner Citadel. It is this fortress, they believed, that protects our soul. Though we might be physically vulnerable, though we might be at the mercy of fate in many ways, our inner domain is impenetrable. As Marcus Aurelius put it (repeatedly, in fact), “stuff cannot touch the soul.” But history teaches us that impenetrable fortresses can still be breached, if betrayed from the inside. The citizens inside the walls—if they fall prey to fear or greed or avarice—can open the gates and let the enemy in. This is what many of us do when we lose our nerve and give in to fear. You’ve been granted a strong fortress. Don’t betray it.
Holiday, Ryan; Hanselman, Stephen. The Daily Stoic: 366 Meditations on Wisdom, Perseverance, and the Art of Living (p. 275). (Function). Kindle Edition.
A good quote.