These Jewish philosophers served the interests of subsequent philosophy in two principal ways. They helped to make the works of Plato and Aristotle accessible to the Scholastics by helping to get them translated from the Arabic versions into Latin, frequently through the medium of Hebrew. (The trans mission was thus very roundabout, as the Arabic versions were in their turn usually based on Syriac translations made by the Nes torians from the Greek originals.) But some of them also exer cised a more direct influence on the Scholastics. Avicebron's Fons Vitae (the Jewish origin of which was not suspected for many centuries) had no small share in moulding the thought of Duns Scotus, among others. And Maimonides exercised an equally strong influence on others, among them the two most important Scholastics, Albertus Magnus and Thomas Aquinas. Maimonides and Crescas also influenced Spinoza in some ways, and both are referred to by him. (See JEWISH PHILOSOPHY.) The chief aim of the Scholastics was to reconcile Christian the ology with philosophy. The first prominent Scholastic was John Scotus Erigena (810-877). He insisted on the harmony of Chris tian dogma with reason, as God is the author of both. Under the influence of a kind of Neo-Platonic mysticism he teaches the idealistic doctrine that things only exist in so far as they are known, that the universal ideas by which they are said to be known are the only ultimate realities and produce the so-called things.
This kind of view about the reality of ideas, now usually called "idealism," was known as "realism" in the middle ages. (Later on "realism" meant, and still usually means, the view that mate rial things are also real, which extreme idealism denied.) In course of time the problem of the reality of universals became a burning question among the Scholastics. It was usually raised in connection with Porphyry's discussion of Aristotle's predicables, but that was a matter of chance; it would probably have arisen in any case in connection with the study of the differences between Platonism and Aristotelianism. Until late in the 11th century, under the predominant influence of Platonism or Neo-Platonism, "realism" was the usual view. Roscelinus ( ?io50-1121) was the first "nominalist," that is to say, he denied the independent reality of universals, and regarded general terms as mere names. For a long period, however, he had no following. Anselm of Canter bury (1033-1109) was a pronounced realist. He also formulated the characteristic view of Scholasticism that faith must precede knowledge—credo ut intelligam.
An innovator was Abelard (1079-1142), famous for his asso ciation with Heloise. His view of universals was rather like that of Avicenna. He held that universals are embodied in the indi vidual things. The "forms" or "ideas," however, are conceived by God from all eternity. The human mind only gets to know them by abstraction from particulars. So universals exist ante res, in rebus, and post res. Abelard is noteworthy for his defence of doubt. He claimed a certain value for it inasmuch as doubt leads to enquiry, and enquiry leads to truth. In his ethical trea tise Scito to ipsum ("Know thyself"—the first separate ethical treatise in the middle ages) Abelard shows himself compara tively tolerant towards pagans, Jews and philosophers or free thinkers.
The Crusades (1097-129o) brought Christendom into contact with Eastern learning and so helped to promote a fuller knowledge of Platonism and Aristotelianism, especially the latter, as ex pounded by Arabian and Jewish philosophers. This tendency
made a good beginning when in 1085 Toledo fell into the hands of the Christians who thus came into possession of numerous philosophical manuscripts. And the movement reached its climax when in the course of the 13th century Aristotelian manuscripts in the original Greek found their way gradually from Constanti nople to the new centres of European learning. Aristotelianism, rejected by the Church in the early part of the 13th century, grew rapidly in favour, especially in the Dominican order, which pro duced the two greatest Aristotelian Scholastics, namely, Albertus Magnus (1193-128o) and Thomas Aquinas (1225-1274), Albertus wrote voluminous expositions of Aristotelianism with the help of Arabian and Jewish commentators, especially Avicenna and Mai monides. In the realm of natural knowledge he respected the authority of Aristotle as much as he trusted Augustine in the sphere of Christian faith. In fact, it was he who first distinguished sharply between natural and theological knowledge—a distinc tion of no little importance in the history of Scholasticism, and even later.
Aristotelian Scholasticism culminated in Thomas Aquinas. He also emphasized the distinction between natural and theological knowledge, between the light of reason (lumen naturale) and the light of revelation, and even admitted, in principle, the autonomy of the former. In practice, however, he subordinated natural to theological knowledge in the sense of making the former aid to the latter. Philosophy is thus treated as the handmaid of theology, and nature as the mere forerunner of grace, though grace is alleged to crown nature, not to reject it. The distinction, though difficult or impossible to maintain, turned out to be helpful inas much as it rendered possible a certain amount of independent thinking in the realm of nature, so long as no reference was made to the concepts of historical Christianity (which constituted the realm of grace). Like Aristotle Aquinas laid great stress on the distinction between matter and form, though he is rather liberal in his conception of the numerous "forms" capable of existing apart from matter. The human soul, though associated with a body, is also capable of separate existence. It is the lowest of the "separate forms," of which there is a scale ascending through all kinds and degrees of angels and spirits (including those which guide the stars and their courses) and culminating in the "absolute form," namely, God. By assuming that God had conferred a measure of autonomy upon nature, Aquinas further facilitated to some extent the possibility of an autono mous philosophy or science. His conception of the character of human knowledge also tended in the same direction. Instead of regarding it (as Augustine had done) as a direct divine illumina tion, Aquinas conceived it to be produced by images which exter nal objects deposit, so to say, in the soul. Empirical studies thus received some recognition. On the question of universals the view of Aquinas was that one "form" is embodied in all the material objects of the same class, and that their matter is re sponsible for their particularity and multiplicity. In the case of Angels, etc., that is, immaterial forms, there is no such multiplicity of replicas, so to say—each form is unique. Our knowledge of material objects qua particulars comes through our senses, but their "form" is apprehended by the intellect.