Dan

“If you know the enemy and know yourself, you need not fear the result of a hundred battles. If you know yourself but not the enemy, for every victory gained you will also suffer a defeat. If you know neither the enemy nor yourself, you will succumb in every battle.”
― Sun Tzu, The Art of War

“Hang on to your youthful enthusiasms -- you’ll be able to use them better when you’re older.”
― Seneca

“We suffer more often in imagination than in reality”
― Lucius Annaeus Seneca