A favorite theme with the writers of the "Books of Chilan Balam" was the cure of diseases. Bishop Landa explains the "_chilanes_" as "sorcerers and doctors," and adds that one of their prominent duties was to diagnose diseases and point out their appropriate remedies.[18-*] As we might expect, therefore, considerable prominence is given to the description of symptoms and suggestions for their alleviation. Bleeding and the administration of preparations of native plants are the usual prescriptions; but there are others which have probably been borrowed from some domestic medicine-book of European origin. The late Don Pio Perez gave a great deal of attention to collecting these native recipes, and his manuscripts were carefully examined by Dr. Berendt, who combined all the necessary knowledge, botanical, linguistic and medical, and who has left a large manuscript, entitled "_Recetarios de Indios_," which presents the subject fully. He considers the scientific value of these remedies to be next to nothing, and the language in which they are recorded to be distinctly inferior to that of the remainder of the "Books of Chilan Balam." Hence, he believes that this portion of the ancient records was supplanted some time in the last century by medical notions introduced from European sources. Such, in fact, is the statement of the copyists of the books themselves, as these recipes, etc., are sometimes found in a separate volume, entitled "The Book of the Jew,"--"_El Libro del Judio_." Who this alleged Jewish physician was, who left so wide-spread and durable a renown among the Yucatecan natives, none of the archaeologists has been able to find out.[18-+] The language and style of most of these books are aphoristic, elliptical and obscure. The Maya language has naturally undergone considerable alteration since they were written; therefore, even to competent readers of ordinary Maya, they are not readily understood. Fortunately, however, there are in existence excellent dictionaries of the Maya of the sixteenth and seventeenth centuries, which, were they published, would be sufficient for this purpose.