In 1463, Pope Pius II (1458–64) addressed a bull of retraction, In Minoribus Agentes, to the rector of the University of Cologne and his scholars. The university had been an important player in the schism separating the Council of Basel (1431–49) from Pope Eugenius IV (1431–47). Pius, as Aeneas Sylvius Piccolomini, had supported the council. Only later did he abandon it for the imperial chancery and the policy of neutrality between pope and council, and then he made his peace with Eugenius, eventually rising to the highest office in the church, while still involved with the council as a conciliar secretary and then a secretary to its pope, Amadeus VIII of Savoy, known as Felix V. On behalf of the conciliar cause he had written a collection of dialogues in 1440. In them Aeneas discussed the active life versus the life of scholarly leisure with the French poet Martin Le Franc, seguing eventually into the relationship of the spiritual and temporal powers. Meanwhile, the jurist Stefano Caccia debated conciliar versus papal power with Nicholas of Cusa. Aeneas had Caccia prevail over Cusanus in this political debate, with Caccia vindicating the conciliarist position his opponent had upheld in his earlier De Concordantia Catholica. In addition, Eneas and Martinus endorse the case Stephanus made against Nicolaus. Nicholas of Cusa would reply to Aeneas in his Dialogus Concludens Errores Amadeistarum. It was this antipapal polemic that Pope Pius wished the readers of his bull to forget.

The University of Cologne was one of the learned institutions that intervened in the polemics following the deposition of Eugenius by the council in 1439. The university supported conciliar supremacy while still adhering to the imperial policy of neutrality in the choice between Basel and the Eugenian council in Florence. In addition, the archbishop of Cologne, Dietrich von Mörs, played a major role in the discussions of princes and prelates of the choice between contending powers, the discussions that created the policy of neutrality. Dietrich even held a local council to discuss these issues. It was in this context that Aeneas composed his work. Not long before, he had composed his De Gestis Concilii Basiliensis Libri Duo, recounting the decision to depose Eugenius and the election of Felix. In 1443 Aeneas also presented the case for Basel in his letter to Hartung von Kappel.

The Libellus Dialogorum received its first modern edition by Adam Franz Kollar in 1761–62, using a Viennese manuscript. In this volume Simona Iaria presents a thorough edition of the text, employing seven manuscripts. The edition is prefaced with a summary of the text, its cultural context, and the surviving manuscripts. Iaria lays out the variants in each copy, dividing the manuscripts into two families (α and β). The stemma at page ccxvii places the four manuscripts in one family and the three in the other into the larger context of lost archetypes and copies. The cultural context is not limited to the fight between pope and council. Iaria discusses the humanistic issues, especially active versus contemplative life, and the value the Renaissance humanists placed on the dialogue as a literary form. The numerous sources employed by Aeneas, classical, patristic, and medieval, are also noted.

The edition is generously spaced with ample annotations. Textual variants are noted at the bottom of each page. Sources and contextual information for each of the fourteen brief dialogues appear in the “Commento” section following the text itself. The actors in the dialogues are noted as Eneas and Martinus, Stephanus and Nicolaus. The editor provides indexes indicating the manuscripts employed, sources employed, and the names appearing in either introduction or edition. Read together with the edition and translation of De Gestis by Denys Hay and W. K. Smith and the text of the letter to Hartung in Rudolf Wolkan’s edition of the letters of Aeneas, the study of Piccolomini’s conciliarism is well served. This edition will wear well unless lost exemplars of the text reappear.