Causa

 The book is divided into seven parts preceded by a prologue, in which the legend of the three Hermes, dating back to the philosopher Albumasar, is narrated.

 The Expositio libelli De substantia orbis, including the four Quaestiones super libello De substantia orbis, contains the "calligraphic" and anonymous transcription of a reportatio based on Pomponatian course of the year 1507.