"I've lost a day!"—the prince who nobly cried,
Had been an emperor without his crown.
Source, in full
Line 99. Suetonius says of the Emperor Titus: "Once at supper, reflecting that he had done nothing for any that day, he broke out into that memorable and justly admired saying, ‘My friends, I have lost a day!'" Suetonius, Lives of the Twelve Cæsars (translation by Alexander Thomson).