From Marcus Aurelius (121–180), Roman emperor from 161 to 180, ruling jointly with Lucius Verus until Verus’ death in 169 and jointly with his son, Commodus, from 177, last of the so-called Five Good Emperors, Meditations:
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.