Papal nuncio to the court of Ferdinand of Hungary. He is remembered entirely because the entry under his name in Bayle’s Dictionnaire historique et critique contains Bayle’s seminal discussion of the philosophy of Leibniz. The official pretext is that Rorarius had maintained that beasts make better use of reason than men do (see also animal thought). This leads Bayle to an extended discussion of the nature of the soul, and eventually of pre-established harmony.