Their main purpose, indeed, was, as one of them declared, to compare the tenets of former teachers with the original handwriting of God, the world and nature. The now almost forgotten contest between the _Realists_ and _Nominalists_ of the middle ages, exercised a decided influence upon the final establishment of the experimental sciences. These were the two philosophic schools which labored respectively to bridge the apparently impassable "gap between thought and actual existence, and the relations between the mind which discerns, and the objects which are discerned." According to Humboldt, "The Nominalists, who only admitted a subjective existence to belong to general ideas in the imagination of man, after many oscillations, ultimately in the fourteenth and fifteenth centuries became the victorious party. From that great aversion to mere abstractions, they first arrived at the necessity of experience, and of increasing the physical basis of knowledge. This direction of their ideas had, at any rate, a secondary influence upon empirical natural science; but even while the views of the Realists still prevailed, the acquaintance with the Arabian literature had diffused a love for Nature's works, in happy contrast with the study of theology, which otherwise absorbed every thing. Thus we see, that in the different periods of the Middle Ages, to which we have been perhaps accustomed to attribute too great a unity of character, in very different courses, namely, in the ideal and the experimental way, the great work of distant discoveries, and the possibility of their being of avail in the extension of the general ideas of the earth, were gradually advanced."