The natural history of Pliny is an unequaled monument of studious diligence and persevering industry. It consists of thirty-seven books, and contains 20,000 facts (as he believed them to be) connected with nature and art, the result not of original research, but, as he honestly confessed, culled from the labors of other men. Owing to the extent of his reading, his love of the marvelous, and his want of judgment in comparing and selecting, he does not present us with a correct view of the science of his own age. He reproduces errors evidently obsolete and inconsistent with facts and theories which had afterwards replaced them. With him, mythological traditions appeared to have almost the same authority as modern discoveries; the earth teems with monsters, not exceptions to the regular order of nature, but specimens of her ingenuity. His peculiar pantheistic belief prepared him to consider nothing incredible, and his temper inclined him to admit all that was credible as true. He tells us of men whose feet were turned backwards, of others whose feet were so large as to shade them when they lay in the sun; others without mouths, who fed on the fragrance of fruits and flowers. Among the lower animals, he enumerates horned horses furnished with wings; the mantichora, with the face of a man, three rows of teeth, a lion's body, and a scorpion's tail; the basilisk, whose very glance is fatal; and an insect which cannot live except in the midst of the flames. But notwithstanding his credulity and his want of judgment, this elaborate work contains many valuable truths and much entertaining information. The prevailing character of his philosophical belief, though tinctured with the stoicism of the day, is querulous and melancholy. Believing that nature is an all- powerful principle, and the universe instinct with deity, he saw more of evil than of good in the divine dispensation, and the result was a gloomy and discontented pantheism. Celsus probably lived in the reign of Tiberius. He was the author of many works, on various subjects, of which one, in eight books, on medicine, is now extant. The independence of his views, the practical, as well as the scientific nature of his instructions, and above all, his knowledge of surgery, and his clear exposition of surgical operations, have given his work great authority; the highest testimony is borne to its merits by the fact of its being used as a text-book, even in the present advanced state of medical science. The taste of the age in which he lived turned his attention also to polite literature, and to that may be ascribed the Augustan purity of his style. Pomponius Mela lived in the reign of Claudius. He is considered as the representative of the Roman geographers. Though his book, "The Place of the World," is but an epitome of former treatises, it is interesting for the simplicity of its style and the purity of its language.