  In De naturalis scientiae constitutione, the first treatise in his collected works on natural philosophy (De rebus naturalibus), Zabarella deals in detail with the questions of the order and perfection of the natural sciences. He claims, for example, that the book on minerals is necessary because the natural philosophy would otherwise be incomplete. The place of the book on minerals in Aristotelian corpus on natural philosophy is immediately after the book On Meteorology. Whether Aristotle himself wrote on minerals is questionable, but he at least recognized the importance of the subject. However, later both Theophrastus and Albertus Magnus wrote on this important subject. Thus Zabarella did not consider Aristotle’s works as a complete corpus to which nothing could be added. In De methodis Zabarella states that Aristotle wrote on subjects of his own choice, but it would be an exaggeration to claim that he was incapable of making mistakes. Aristotle was not infallible and it would be erroneous to insist that he knew the truth of everything he wrote. Nevertheless, he was an outstanding scholar in Zabarella’s view, who, for example, turned the study of logic into a discipline.