[Sidenote: Moslem, Jewish, and other influences on Castilian thought and science.]
The oriental influence on Castilian thought and science, or rather the classical influences transmitted through Moslem and Jewish writers, advanced for a time, and continued to be preponderant until the fifteenth century, when European ideas, principally Italian, became the more important. There was a change in direction of the Moslem influence, however. Philosophy dropped back from the leading place, and was substituted by juridical and moral studies, while the physical and natural sciences, including their superstitious derivations, acquired a remarkable vogue. Christian writers imitated Moslem philosophers and moralists, or translated their works; many Castilian writers were of Moslem or Jewish origin, or still continued to belong to those peoples and faiths; many Arabic works were included in the libraries of the time; and the oriental form of scientific exposition, the encyclopedia, was frequently used. The oriental influence manifested itself especially in the natural sciences. Books of mathematics, physics, chemistry, medicine, and astronomy were almost the only ones to be translated from the Arabic, and these branches were also the ones to which Mudéjar scholars of the period most frequently devoted themselves. Moslems and Jews continued to be the most famous physicians of Castile. The deductive method and dialectic forms were still employed by them, rather than personal observation and experiment. The most marked characteristic of the cultivation of the natural sciences was in their extravagant applications with a view to a knowledge of the future or to obtain vast wealth through supernatural agencies. Thus chemistry tended toward alchemy, with the aim of finding the philosopher’s stone, whereby base metals might be turned into gold, or with the object of producing mysterious elixirs endowed with wonder-working virtues. Chemists and alchemists came to be considered as practicers of magic arts in more or less intimate communion with the Devil, a belief in which the individuals themselves often shared. Men of high attainments were credulous exponents of these superstitions,--for example, Archbishop Alonso de Carrillo and the learned Enrique de Villena; the latter attained to a legendary fame which has endured even to the present day. Similarly, astronomers were at the same time astrologers. Both alchemy and astrology served a useful purpose, however, in stimulating the study of the true sciences, with a resulting advance in knowledge. The age of the Moslem and Jewish philosopher was past, and very little that was original in the realm of philosophy appeared in Castile in this period; even theological writings were not prominent, despite the study of theology in the universities and schools. Moral and political literature abounded, such as discussions of the wiles or virtues of women on the one hand, and works on the relations between church and state on the other. In the latter respect ecclesiastical writers maintained the superior authority of the pope over the king, but were in the main defenders of monarchy, although distinguishing the legitimate king from the tyrant, and sustaining the ultimate dependence of the monarch on his people. The Italian influence appeared in philosophy through translations of classical (Aristotle, Plato, Cicero, Seneca) and contemporary Italian (Colonna, Petrarch, Boccaccio) texts. The most influential manifestation of Castilian thought was in the field of jurisprudence, to which references have already been made in dealing with the _Partidas_ and other legal volumes. The entire period abounded in this type of literature, not only in compilations of an official character, but also in those of private individuals, all of them greatly influenced by the legal works of Justinian.