Tranquility can't be grasped
except by those who have reached an unwavering and firm power of judgment
—the rest constantly fall and rise in their decisions,
wavering in a state of alternatively rejecting and accepting things.
What is the cause of this back and forth?
It's because nothing is clear and they rely on the most uncertain guide - common opinion.
— Seneca, Moral Letters, 95.57b-58a (resource) Ryan Holiday, The 366 Meditations on Wisdom, Perseverance, and the Art of Living—