M. Russell Thayer, "The Life, Character, and Writings of Francis Lieber. A Discourse Delivered before the Historical Society of Pennsylvania, January 13, 1873," in Francis Lieber, Reminiscences, Addresses, and Essays
(Philadelphia: J.B. Lippincott & Co., 1881), pp. 13-44 (at 41-42):
It was his habit in reading or studying to use a great number of book-marks. These consisted of narrow strips of pasteboard, upon each one of which was usually written some important historical date, some pregnant maxim, or some weighty saying. He was exceedingly industrious, as may be easily seen in the great number and variety of his productions. His table and every chair in the room were always covered with books and papers. He was very seldom idle. At one period of his student life in Germany he allowed himself only four hours of sleep, and his food at that period often consisted of nothing but bread and apples. While in South Carolina it was his habit to write at his books until one o'clock and often later in the night, and afterwards to rise early enough to be in his class-room and deliver his lecture from seven to eight o'clock; always preferring that hour that he might have more time during the day for his own work. Over the door of his house in New York he had placed “Die Studirende Eule”—the owl studying; and on the ceiling were painted these words:
Over the door of his library hung the panel of a bench saved from the fire which destroyed the chapel of South Carolina College, on which he had painted the saying of Socrates, ΧΑΛΕΠΑ ΤΑ ΚΑΛΑ—all noble things are difficult. On the seal, which he adopted in his youth, were the words Perfer et Sperne. In his library hung what he called his Stella duplex—William of Orange and Washington, engravings of whom he had arranged and framed upon one card, with, on one side, the motto of William of Orange, Saevis tranquillus in undis, and on the other (Washington having no motto of his own) Tenax et Integer. Another Stella duplex, similarly arranged, contained the likenesses of Hampden and Pym: above them the words Nulla vestigia retrorsum, and underneath,
In his bedroom he had busts of Plato, Schiller, and Alexander Hamilton, whom he greatly admired, and over the mantelpiece, his favorite—Hugo Grotius.
Probis et audacibus
Heres gratus et compos
Hat tip: Ian Jackson.