 The second step, hence, consists in collecting and presenting with the same faithfulness old and new hypotheses that have been suggested to account for the phenomena. Sturm meticulously presents hypotheses old and new, from Pre-Socratic to seventeenth-century authors (see  sect. 1.2).  Sturm shows himself to be an assiduous, diligent reader of the natural philosophy available at his time. His knowledge of more and even less prominent authors is impressive and precise.