In the constitution of that rational animal I see no virtue which is opposed to justice, but I see a virtue which is opposed to love of pleasure, and that is temperance. Book VIII

Never, never, never believe any war will be smooth and easy, or that anyone who embarks on the strange voyage can measure the tides and hurricanes he will encounter. The statesman who yields to war fever must realise that once the signal is given, he is no longer the master of policy but the slave of unforeseeable and uncontrollable events. Antiquated War Offices, weak, incompetent, or arrogant Commanders, untrustworthy allies, hostile neutrals, malignant Fortune, ugly surprises, awful miscalculations — all take their seats at the Council Board on the morrow of a declaration of war. Never Give In!

Variant: Death hangs over thee. While thou livest, while it is in thy power, be good. Book IV

Self-control and resistance to distractions. Optimism in adversity—especially illness. Book I