Being brave. Finding the right balance. These are core Stoic virtues, but in their seriousness, they pale in comparison to what the Stoics worshipped most highly: Doing the right thing.
There is no Stoic virtue more important than justice, because it influences all the others. Marcus Aurelius himself said that justice is “the source of all the other virtues.”
Stoics throughout history have pushed and advocated for justice, oftentimes at great personal risk and with great courage, in order to do great things and defend the people and ideas that they loved.
Courage. Temperance. Justice. These are the critical virtues of life. (Source: DailyStoic.com)
A must-read book on stoicism: The Daily Stoic: 366 Meditations on Wisdom, Perseverance, and the Art of Living.