What is peculiar to "summists" or "sententiaries", as the authors of these works are called, is the adoption of the method first suggested by Gerbert in his "De Rationali et Ratione Uti", and used by Abelard in his "Sic et Non", consisting in an exposition of contradictory views, the affirmative and negative.
Progress towards the final form of the thirteenth-century "Summæ" is marked by the greater care which was taken, as time went on, to explain in a systematic manner the apparent contradiction among the conflicting opinions presented.
Finally the summists adopted more or less unanimously a fixed division of the field of theology and philosophy, and adhered more or less closely to a definite order of topics, although varying in their arrangement.
How far Peter Lombard was influenced by earlier summists, such as Robert Pullen, Hugh of St. Victor and the author of the "Summa Sententiarum" which was immediately inspired by Abelard's work, historians have not determined.
He deserves his renown as the first great summist chiefly because, in spite of the opposition which his work met during his lifetime, its influence grew greater in time, until in the thirteenth century it was universally adopted as a text.
Notwithstanding all that hostile critics of Scholasticism have said about the dryness and unattractiveness of the medieval "Summæ", these works have many merits from the point of view of pedagogy, and a philosophical school which supplements, as Scholasticism did, the compendious treatment of the "Summæ", with the looser form of treatment of the "Quæstiones Disputatæ" and the "Opuscula", unites in its method of writing the advantages which modern philosophy derives from the combination of textbook and doctor's dissertation.
[8] The chief manual of confessors is that of Paul of Hungary composed for the Brothers of St. Nicholas of Bologna (1220–21) and edited without mention of the author in the "Bibliotheca Casinensis"[9] and with false assignment of authorship by Raymund Duellius.
The manuals for confessors of John Nieder (d. 1438), St. Antoninus, Archbishop of Florence (d. 1459), and Girolamo Savonarola (d. 1498) were much esteemed in their time[11][12] In the area of Law, the summa is a practical and didactic genre, that was developed from the methodology of the gloss.
In order to achieve this goal, easy, simple and systematic summaries of whole works were made, and the literary genre of the summae in the legal area was born.