In his Practica geometriae plain traces of the use of the Roman agrimensores are met with; in his Liber abaci old Egyptian problems reveal their origin by the reappearance of the very numbers in which the problem is given, though one cannot guess through what channel they came to Leonardo's knowledge.
In 1202 he was again in Italy and published his great work, Liber abaci, which probably procured him access to the learned and refined court of the emperor Frederick II.
His great work was the Liber de Corpore et Sanguine Domini (first ed.
See also the same writer's Etude sur le Liber pontificalis (Paris, 1877); and the article by A.
On the maps illustrating the encyclopaedic Liber floridus by Lambert, Lambert Liber flori dus 1120 FIG.
Then appeared, under the influence of the school of law at Pavia, the Liber legis Langobardorum, also called Liber Papiensis (beginning of Tith century), and the Lombarda (end of 11th century) in two forms - that given in a Monte Cassino MS. and known as the Lombarda -Casinensis, and the Lombarda Vulgata.
At most all that was asked was whether those decretals which did not appear in the Liber canonum (the collection of Dionysius Exiguus, accepted in France) had the force of law, but Pope Nicholas having answered that all the pontifical letters had the same authority (see Deer.
The Liber abaci, which fills 459 printed pages, contains the most perfect methods of calculating with whole numbers and with fractions, practice, extraction of the square and cube roots, proportion, chain rule, finding of proportional parts, averages, progressions, even compound interest, just as in the completest mercantile arithmetics of our days.
He had earlier opened a correspondence with Augustine, along with his friends Tyro and Hilarius, and although he did not meet him personally his enthusiasm for the great theologian led him to make an abridgment of his commentary on the Psalms, as well as a collection of sentences from his works - probably the first dogmatic compilation of that class in which Peter Lombard's Liber sententiarum is the best-known example.
The author of the Liber also claims that Chlodio was the son of Pharamund, but this personage is quite legendary.