It will be seen that both students and professors were bound to the text, as were the teachers of the Seven Liberal Arts in the cathedral schools before them. There was no appeal to the imagination, still less to observation, experiment, or experience. Each generation taught what it had learned, except that from time to time some thinker made a new organization, or some new body of knowledge was unearthed and added. Another method much used was the debate, or disputation, and participation in a number of these was required for degrees (R. 116). These disputations were logical contests, not unlike a modern debate, in which the students took sides, cited authorities, and summarized arguments, all in Latin. Sometimes a student gave an exhibition in which he debated both sides of a question, and summarized the argument, after the manner of the professors. As a corrective to the memorization of lectures and texts, these disputations served a useful purpose in awakening intellectual vigor and logical keenness. They were very popular until into the sixteenth century, when new subject-matter and new ways of thinking offered new opportunities for the exercise of the intellect. [Illustration: FIG. 66. A UNIVERSITY DISPUTATION (From Fick's _Auf Deutschland's Höhen Schulen_)] In teaching equipment there was almost nothing at first, and but little for centuries to come. Laboratories, workshops, _gymnasia_, good buildings and classrooms--all alike were equally unknown. Time schedules of lectures (Rs. 122, 123) came in but slowly, in such matters each professor being a free lance. Nor were there any libraries at first, though in time these developed. For a long time books were both expensive and scarce (Rs. 78, 119, 120). After the invention of printing (first book printed in 1456), university libraries increased rapidly and soon became the chief feature of the university equipment. Figure 65 shows the library of the University of Leyden, in Holland, thirty-five years after its foundation, and about one hundred and fifty years after the beginnings of printing. It shows a rather large increase in the size of book collections [25] after the introduction of printing, and a good library organization. [ILLUSTRATION: FIG 67. A UNIVERSITY LECTURE AND LECTURE ROOM (From a woodcut printed at Strassburg, 1608)]