The Neo-Platonists showed some interest in alchemy as well as in theurgy and astrology. Berthelot published in his _Collection des Alchimistes Grecs_ “a little tract of positive chemistry” which is extant under the name of Iamblichus; and Proclus treated of the relations between the metals and planets and the generation of the metals under the influence of the stars.[1438] Of Synesius, who was both a Neo-Platonist and a Christian bishop, and who seems to have written works of alchemy, we shall treat in a later chapter. CHAPTER XII AELIAN, SOLINUS AND HORAPOLLO Aelian _On the Nature of Animals_—General character of the work—Its hodge-podge of unclassified detail—Solinus in the middle ages—His date—General character of his work; its relation to Pliny—Animals and gems—Occult medicine—Democritus and Zoroaster not regarded as magicians—Some bits of astrology—Alexander the Great—The _Hieroglyphics_ of Horapollo—Marvels of animals—Animals and astrology—The cynocephalus—Horapollo the cosmopolitan. [Sidenote: Aelian _On the Nature of Animals_.] From mystic and theurgic compositions we return to works of the declining Roman Empire which deal more directly with nature but, it must be confessed, in a manner somewhat fantastic. About the beginning of the third century, Aelian of Praeneste, who is included by Philostratus in his _Lives of the Sophists_, wrote _On the Nature of Animals_.[1439] Its seventeen books, written in Greek, which Aelian used fluently despite his Latin birth, are believed to have reached us partly in interpolated form through two families of manuscripts, of which the older and less interpolated text is found in a thirteenth century manuscript at Paris and a somewhat earlier Vatican codex.[1440] A number of its chapters are similar to and perhaps borrowed from Pliny’s _Natural History_; at any rate they are commonplaces of ancient science; but the work also has a marked individuality. Parallels have also been noted between this work and the later _Hexaemeron_ of the church father Basil. Aelian was much cited in Byzantine literature and learning, and if he was not directly used in the Latin west, at least the attitude toward animals which he displays and his selection of material concerning them are as apt precursors of medieval Latin as of medieval Greek scientific literature. [Sidenote: General character of the work.]