Johannes de Porta is associated with one work in the Chantilly Codex, the four-voice Isorhythmic motet "Alma polis religio/Axe poli cum artica." This is one of the last motets found in the Chantilly Codex and contains the names of several poets and composers presumably belonging to the Augustan order; de Porta identifies himself as "the composer." The text is a difficult one to interpret, and sometimes this piece has been accredited to "Egidius de Aurolia" (Gilles of Orleans) as the text states that "from him, all melody flows." Just who is precisely meant of the many Aegidiuses or Egidiuses known from fourteenth century France is unclear, and as the otherwise unknown de Porta appears to have signed the work internally, there remains little doubt that, whoever he was, he was the actual writer of "Alma polis religio/Axe poli cum artica." For a work composed at the start of the fifteenth century, it demonstrates uncommon skill and is in advance of its time.