No tree becomes deep-rooted and sturdy unless strong winds blow against it. This shaking and pulling is what makes the tree tighten its grip and plant its roots more securely; the fragile trees are those grown in a sunny valley. "Why then," asks Seneca, "do you wonder that good men are shaken in order that they may grow strong?" Just like for the trees, heavy rains and strong winds are to the advantage of good people, it's how they may grow calm, disciplined, humble, and strong.
- From The Little Book of Stoicism: Timeless Wisdom to Gain Resilience, Confidence, and Calmness by Jonas Salzgeber