The character of Frederick is one of extraordinary interest and versatility, and contemporary opinion is expressed in the words _stupor mundi et immutator mirabilis_. Licentious and luxurious in his manners, cultured and catholic in his tastes, he united in his person the most diverse qualities. His Sicilian court was a centre of intellectual activity. Michael Scott, the translator of some treatises of Aristotle and of the commentaries of Averroes, Leonard of Pisa, who introduced Arabic numerals and algebra to the West, and other scholars, Jewish and Mahommedan as well as Christian, were welcome at his court. Frederick himself had a knowledge of six languages, was acquainted with mathematics, philosophy and natural history, and took an interest in medicine and architecture. In 1224 he founded the university of Naples, and he was a liberal patron of the medical school at Salerno. He formed a menagerie of strange animals, and wrote a treatise on falconry (_De arte venandi cum avibus_) which is remarkable for its accurate observation of the habits of birds.[1] It was at his court, too, that--as Dante points out--Italian poetry had its birth. Pier della Vigna there wrote the first sonnet, and Italian lyrics by Frederick himself are preserved to us. His wives were kept secluded in oriental fashion; a harem was maintained at Lucera, and eunuchs were a prominent feature of his household. His religious ideas have been the subject of much controversy. The theory of M. Huillard-Breholles that he wished to unite to the functions of emperor those of a spiritual pontiff, and aspired to be the founder of a new religion, is insufficiently supported by evidence to be credible. Although at times he persecuted heretics with great cruelty, he tolerated Mahommedans and Jews, and both acts appear rather to have been the outcome of political considerations than of religious belief. His jests, which were used by his enemies as a charge against him, seem to have originated in religious indifference, or perhaps in a spirit of inquiry which anticipated the ideas of a later age. Frederick's rule in Germany and Italy was a failure, but this fact may be accounted for by the conditions of the time and the inevitable conflict with the papacy. In Germany the enactments of 1220 and 1231 contributed to the disintegration of the Empire and the fall of the Hohenstaufen, while conflicting interests made the government of Italy a problem of exceptional difficulty. In Sicily Frederick was more successful. He quelled disorder, and under his rule the island was prosperous and contented. His ideas of government were those of an absolute monarch, and he probably wished to surround himself with some of the pomp which had encircled the older emperors of Rome. His chief claim to fame, perhaps, is as a lawgiver. The code of laws which he gave to Sicily in 1231 bears the impress of his personality, and has been described as "the fullest and most adequate body of legislation