“When you know a thing, to hold that you know it; and when you do not know a thing, to allow that you do not know it: this is knowledge.” — Confucius · Analects, 2.17
“The man who learns but does not think is lost. The man who thinks but does not learn is in great danger.” — Confucius · Analects, 2.15
“He is a wise man who does not grieve for the things which he has not, but rejoices for those which he has.” — Epictetus · Fragments
“Begin at once to live, and count each separate day as a separate life.” — Seneca · Letters to Lucilius
“Loss is nothing else but change, and change is Nature's delight.” — Marcus Aurelius · Meditations, Book IX
“Never let the future disturb you. You will meet it, if you have to, with the same weapons of reason which today arm you against the present.” — Marcus Aurelius · Meditations, Book VII
“How long are you going to wait before you demand the best for yourself?” — Epictetus · Discourses, Book I