Augustine to Galileo: The History of Science, A.D. 400- 1650

(1) EXPLANATION OF CHANGE AND CONCEPTION OF SUBSTANCE

THE SYSTEM OF SCIENTIFIC thought that was made known to Western Christians in the 13th century came to them, in a collection of translations from Greek and Arabic, as a complete and for the most part coherent whole. This was a system of rational explanations in power and range quite beyond anything known earlier in the Latin West, and one the general principles of which in fact dominated European science until the 17th century. This Greco-Arabic scientific system was not, however, received merely passively in the 13th century. The activity of mind that had shown itself in the 12th century in the fields of philosophy and technology was applied in the 13th century to detect, and to endeavour to resolve, the contradictions that existed within the Aristotelian system itself, between Aristotle and other authorities such as Ptolemy, Galen, Averroës and Avicenna, and between the various authorities and observed facts. The Western scholars were trying to make the natural world intelligible and they seized upon the new knowledge as a wonderful, but not final, illumination of mind and as a starting-point for further investigation.

The object of this chapter is to describe this 13th-century scientific system, indicating the historical sources of each part of it, and to give a brief account of the additions of fact and modifications in detail made to it during the century or

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