So jealous was he of every moment lost.

From Pliny the Younger to Baebius Macer.  In this letter, Pliny the Younger lists the works of his uncle, Pliny the Elder, and describes his work ethic.  From Book 3 Pliny the Younger Letters, translated by J.B. Younger.  It is such a common pattern - those who accomplish much work extraordinarily hard.  

[5] L   To Baebius Macer.

I was delighted to find that you are so zealous a student of my uncle's books that you would like to possess copies of them all, and that you ask me to give you a complete list of them. I will play the part of an index for you, and tell you, moreover, the order in which they were written, for this is a point that students are interested to know.

"Throwing the Javelin from Horseback," one volume; this was composed, with considerable ingenuity and research, when he was on active service as a cavalry lieutenant {praefectus alae}. 

 

"The Life of Pomponius Secundus," two volumes; - Pomponius was remarkably attached to my uncle, who, so to speak, composed this book to his friend's memory in payment of his debt of gratitude. 

 

"The German Wars," twenty volumes; - this comprises an account of all the wars we have waged with the German races. He commenced it, while on service in Germany, in obedience to the warning of a dream, for, while he was asleep, the shade of Drusus Nero, who had won sweeping victories in that country and died there, appeared to him and kept on entrusting his fame to my uncle, beseeching him to rescue his name from ill-deserved oblivion. 

 

"The Student," three volumes, afterwards split up into six on account of their length; - in this he showed the proper training and equipment of an orator from his cradle up.

"Ambiguity in Language," in eight volumes, was written in the last years of Nero's reign when tyranny had made it dangerous to write any book, no matter the subject, in anything like a free and candid style. 

 

"A Continuation of the History of Aufidius Bassus," in thirty-one books. 

 

"Natural History," in thirty-seven books; - a comprehensive and learned work, covering as wide a field as Nature herself.

Does it surprise you that a busy man found time to finish so many volumes, many of which deal with such minute details? You will wonder the more when I tell you that he for many years pleaded in the law courts, that he died in his fifty-seventh year, and that in the interval his time was taken up and his studies were hindered by the important offices he held and the duties arising out of his friendship with the Emperors. But he possessed a keen intellect; he had a marvellous capacity for work, and his powers of application were enormous. He used to begin to study at night on the Festival of Vulcan, *   not for luck but from his love of study, long before dawn; in winter he would commence at the seventh hour or at the eighth at the very latest, and often at the sixth. He could sleep at call, and it would come upon him and leave him in the middle of his work. Before daybreak he would go to Vespasian - for he too was a night-worker - and then set about his official duties. On his return home he would again give to study any time that he had free. Often in summer after taking a meal, which with him, as in the old days, was always a simple and light one, he would lie in the sun if he had any time to spare, and a book would be read aloud, from which he would take notes and extracts. For he never read without taking extracts, and used to say that there never was a book so bad that it was not good in some passage or another. After his sun bath he usually bathed in cold water, then he took a snack and a brief nap, and subsequently, as though another day had begun, he would study till dinner-time. After dinner a book would be read aloud, and he would take notes in a cursory way. I remember that one of his friends, when the reader pronounced a word wrongly, checked him and made him read it again, and my uncle said to him, "Did you not catch the meaning?" When his friend said "yes," he remarked, "Why then did you make him turn back? We have lost more than ten lines through your interruption." So jealous was he of every moment lost.