Cassius Dio (Roman statesman and historian, c. 163-235)
“Keep your weapons always ready to hand, but do not use them either against one another or against those who are at peace.”
- From Cassius Dio’s The Roman History (Book 53, chapter 10), translated by Ian Scott-Kilvert (Penguin Classics, 1987). Dio wrote this quote in the character of Octavian for a scene where Octavian gives a speech about remaining in power as a dictator.