The Aristotelian natural corpus covered a wide range of subjects in a number of separate texts: while the Physics was a sort of general work—which appeared to some fifteenth- and sixteenth-century authors more metaphysical, even overlapping with the Metaphysics—the other treatises represented different sections of natural philosophy on particulars. The success and influence of Aristotelian natural philosophy was due to its centrality to university teaching, where it was favored because it covered every topic, like an encyclopedia. Few attempts were made to reconsider which texts represented the core of the study of natural philosophy in the universities; one remarkable exception was Pierre de la Ramée (1515–1572), who put a distinctive emphasis on particular sciences at the expense of study of the Physics. Physics, along with On the Heavens, Meteorology, and On Generation and Corruption, was the main reference for natural philosophy in the traditional curricula of the Faculty of Arts. Universities—especially in Italy—appointed many lecturers in natural philosophy, who usually received high salaries. In the second half of the sixteenth century, separate chairs, of botany, mathematics, and even chemistry (in Mantua and Germany), were established. Aristotelian texts were traditionally studied according to the commentaries by Averroes (which provided the internal partition of the texts into sections).