The categories in Petrus Hispanus’s Tractatus commentators: John Buridan, John Versor and Peter Tartaret

Mário João Correia

Instituto de Filosofia, Universidade do Porto, Portugal
ORCID: 0000-0001-7883-0950

Recibido: 10 de diciembre 2020; aceptado: 2 de febrero 2021

Abstract

One of the features of the manuscript transmission of Petrus Hispanus’s Tractatus (or Summulae logicales) is the fact that the treatise on the Categories does not always appear in the same place. In some manuscripts, it appears in third place, after the treatise on Porphyry’s Isagoge, following the traditional order of the logica vetus. But in some others, the treatise on the Categories appears in fifth place, after the treatise on the Topics and right before the treatise on supposition. In both cases, it seems that the place of Aristotle’s Categories in logic is defined by the notion of “term”.

The purpose of this article is to understand why this variation occurs, since it is not theoretically neutral. Hence, to address the problem of placing the treatise on the Categories within logic, three of the most prominent Tractatus commentators will be presented: John Buridan, John Versor and Peter Tartaret. This exercise will provide some insights on the relation between the categories and the theory of supposition, and also on the vexata quaestio of what categories are about (words, concepts, or things).

Keywords: Petrus Hispanus’ Tractatus, Categories, Term, Supposition, Logic.

Las categorías en los comentadores de los Tractatus de Pedro Hispano: Juan Buridán, Juan Versor y Pedro Tartaret

Resumen

Una de las características de la transmisión manuscrita de los Tractatus (o Summulae logicales) de Pedro Hispano es el hecho de que el tratado sobre las Categorías no siempre ocupa el mismo lugar al interior de la obra. En algunos manuscritos se encuentra en tercer lugar, después del tratado acerca de la Isagoge de Porfirio, siguiendo el orden tradicional de la logica vetus. Pero en algunos otros, se encuentra en quinto lugar, después del tratado sobre los Tópicos y antes del tratado sobre la suposición. En los dos casos, el lugar de las Categorías de Aristóteles en la lógica es definido por la noción de “término”.

El propósito de este artículo es entender por qué ocurre esta variación, ya que no es teóricamente neutral. Por tanto, para atender al problema del orden de aparición del tratado sobre las Categorías dentro de la lógica, se presentarán tres de los más destacados comentaristas de los Tractatus: Juan Buridan, Juan Versor y Pedro Tartaret. Este ejercicio proporcionará algunas conclusiones sobre la relación entre las categorías y la teoría de la suposición, y también sobre la vexata quaestio acerca del sujeto de las categorías (palabras, conceptos, o cosas).

Palabras clave: Tractatus de Pedro Hispano, Categorías, Término, Suposición, Lógica.

Introduction

Petrus Hispanus’s Tractatus is the only logic textbook of its period that includes a treatise on Aristotle’s Categories. Although the Categories is seen as part of the logica vetus, its place within logic, and also within philosophy were a matter of debate. Is the Categories a book about words? About concepts? About things? About all of them? Another question which is at least partially influenced by this debate is the question about the completeness and sufficiency of the Aristotelian list of ten categories.

The tension posited by these problems has a direct influence on the manuscript tradition of Petrus Hispanus’s Tractatus. In some manuscripts, the treatise on the Categories (De predicamentis) appears in the third place: the first treatise is an introduction that deals with the notions of noun (nomen), verb (verbum), phrase (oratio) and proposition (propositio), and the second treatise discusses the contents of Porphyry’s Isagoge. Thus, in these manuscripts, the treatise on the Categories follows the traditional order of the logica vetus. But in some others, that is not the case. The treatise on the Categories appears in the fifth place, after the treatise on the Topics (De locis) and right before the treatise on supposition (De suppositionibus). In this way, the Categories are read as an introduction to the properties of terms (passiones terminorum). In both cases, it seems that the place of the Categories in logic follows a traditional division of the subject-matter of logic, i.e., the syllogism. The Categories would deal with the pars integralis remota of the syllogism: the term (terminus). However, the scholastic logicians started to create and develop a theory of the properties of terms (supposition, distribution, restriction, etc.) that did not fit any of the Aristotelian works, and some authors thought to be more appropriate to add the Categories to this context.

Recently, a diplomatic edition of the Tractatus in the Tarragona, Arxiu Històric Arxidiocesà, Ms. 2 (85) was published.1 This manuscript was used as the main witness by Lambert Marie De Rijk to make his critical edition of Petrus Hispanus’s Syncategoreumata (1992). However, when he prepared the Tractatus’s critical edition (1972), he did not have access to this witness. It is plausible that the Tractatus and the Syncategoreumata were written together and then started to be separated and read as autonomous works in the manuscript transmission. Despite this plausible hypothesis, there is at least one manuscript which contains Tractatus and Syncategoreumata together but in there, the seventh treatise of the Tractatus was substituted by Pseudo-Thomas’s De falaciis (cf. Firenze, Biblioteca Medicea Laurenziana, Ms. Fiesolano 145, ff. 35ra-46va). For this reason, there is not a sufficient criterium to choose what the best witnesses of the Tractatus are. Still, according to De Rijk (1972, p. cx), the Tarragona manuscript is supposed to be one of the most reliable witnesses. The treatise on the Categories also appears there in the fifth place, not in the third.

Here is the comparison between De Rijk’s critical edition and the Tarragona witness in what concerns the order of the treatises:2

De Rijk’s critical edition: 1) De introductionibus 2) De praedicabilibus 3) De praedicamentis 4) De sillogismis 5) De locis 6) De suppositionibus 7) De fallaciis 8) De relativis 9) De ampliationibus 10) De appellationibus 11) De restrictionibus 12) De distributionibus

Tarragona, AHA, Ms. 2 (85): 1) De introductionibus 2) De praedicabilibus 3) De sillogismis (4) 4) De locis (5) 5) De praedicamentis (3) 6) De suppositionibus 7) De fallaciis 8) De relativis 9) De ampliationibus 10) De appellationibus 11) De restrictionibus 12) De distributionibus

I am not going to discuss and clarify here the Tractatus’s date and place of production. It is a highly problematic issue since some of the circumstantial evidence De Rijk used to say that this work dates back roughly to somewhere between 1220 and 1250 and is written by the Pope John XXI is now known to be wrong. The reason why there are not any commentators before the decade of 1280 is also incomprehensible. Since it is likely that the first commentator may be Robertus Anglicus or a Simon which was thought to be Simon of Faversham, how to explain this thirty –or forty– year gap? Until now, I could not find a satisfying methodology to solve this problem.3

My purpose here is different and more modest: I want to show that the hesitation about the place of the treatise on the Categories is rooted in the theoretical problem about the so-to-say “ontological” status of the categories and their relation to the notion of “term” (terminus). In order to make my point, I chose three (out of hundreds) of Petrus Hispanus’s commentators separated in both time and philosophical approach: John Buridan, John Versor and Peter Tartaret.

This is not an arbitrary choice. First of all, although there are hundreds of commentaries to the Tractatus, most of them do not cover all the treatises,4 and even more, a good amount of them do not even comment Petrus Hispanus’s text in itself but use it as a scheme to pose problems or to organize sets of questions (cf. e.g. Blaise de Parme, 2001), not to mention the extreme case of Tomás de Mercado’s Commentarii lucidissimi in textum Petri Hispani, which does not use any element of the treatises at all, as if “textus Petri Hispani” was a literary genre, and not a particular work.

The three chosen commentators, on the contrary, produced a complete commentary, despite some particularities that will be highlighted. Buridan’s commentary is a landmark since he was plausibly the first author to comment the Tractatus at the University. The influence of his commentary was enormous in the second half of the 14th century and beyond, through the printed editions with Johannes Dorp’s annotations.

In a lesser degree, Versor and Tartaret were very influential too. John Versor is surely one of the most important authors of the second half of the 15th century, and his commentary is extant in at least 33 manuscripts (Meirinhos, 2011: 600) and 10 printed editions from the 15th and 16th centuries. Peter Tartaret’s commentary has also been printed and reprinted several times (at least 12) until well into the 17th century (Geudens, 2020).

It would be impossible to state a general conclusion about the order of the treatise on the Categories by looking at only three commentators. Yet, they can give us an outline of the problem the authors who wanted to order coherently the various parts of logic had to face.

1. John Buridan

As pointed before, Buridan might have been the first author to use Petrus Hispanus’s Tractatus as a textbook at the university level. Before him, these treatises were a study tool in the context of the provincial schools of some religious orders (Maierù, 1994: 12). His commentary is dated sometime between 1325 and 1360. The lemmata he comments on are many times different from any version of the Tractatus. This also happens in the treatise on the Categories. Moreover, Buridan attaches together the treatises VI and VIII to XII, which are originally small treatises about supposition and the properties of terms. However, the text he comments on does not appear even in any interpolated text of the Tractatus. It is possible, then, that Buridan created the text that is being commented on. He also added at the end a treatise about demonstration to overcome the absence of a treatise on the Posterior Analytics. With all these changes, we could ask: why did he use the Tractatus at all? Maybe the answer is that he wanted a text that would be sufficiently well organized to cover all the matters of logic. He was not very interested in the text itself and it seems that his disappointment with the text grows when it comes to the properties of terms. In the case of the commentary on the treatise on the Categories, Buridan is clearly more interested in Aristotle himself, and in the Liber sex principiorum than in Petrus Hispanus’s text, which is not very original and mostly copies or abbreviates parts of Boethius or of Aristotle (Bos, 1994: xvii-xix). So, this is not very surprising.

As for the order of the treatises, what he did was more or less the opposite of what happens in the Tarragona manuscript: instead of putting the treatise on the Categories in the fifth place in order to join it with the treatise on supposition, he moved the treatise on supposition to the fourth place. In this way, he also joined the two treatises.

The order of the treatises in Buridan commentary is as follows:

1) De introductionibus/De propositionibus (1)
2) De praedicabilibus (2)
3) De praedicamentis (3)
4) De suppositionibus (6 + 8-12)
5) De sillogismis (4)
6) De locis (5)
7) De fallaciis (7)
8) De demonstrationibus (on the Posterior Analytics, absent from the Tractatus)

Within the text of the De suppositionibus, Buridan explains the choice of making the treatise on supposition follow the treatise on the Categories by saying:

Quia non est propositionis supponere, sed termini qui est subiectum vel praedicamentum, ideo post tractatum de praedicamentis debet sequi iste tractatus quartus, qui est de suppositionibus et quibusdam eis annexis (Summ. de Supp. 4.1.1: 7).

Since supposition belongs not to a proposition but to a term that can be the subject or the predicate of a proposition, the fourth treatise, dealing with supposition and some related matters, has to follow the treatise on predicamental terms (praedicamenta) (transl. Klima, 2001: 221).

In fact, he intends to order the treatises from the starting point of a traditional view on the subject-matter of logic: logic’s subject-matter is the syllogism, which is composed by propositions (proximate integral parts), which in turn are composed by terms (proximate integral parts of propositions, and so, remote integral parts of the syllogism). For him, both treatises, on the Categories and on the supposition, are about the part of logic that deals with terms.

So, what is a category for Buridan? What does he mean by a “term” in this context? First, we must say that a term, as a part of a proposition, can be taken in three ways, such as the proposition itself: written, spoken or mental. Although Buridan is generally more interested in the mental aspect of terms, he takes the conventional character of attributing a signification to a sign very seriously. A term is a sign which contains two main properties (passiones): a significatio and a suppositio. For him, the distinction of the categories is not a distinction between several res, but between several rationes or modi praedicandi of a substance (Summ. in Praed. 3.1.5: 14-15). He clearly states that the same noun can belong to different categories according to different connotations (connotationes), i.e., according to the several ways in which this noun is a sign of something else besides what is being supposed. Only substance has not got a connotatio. And besides substance, only some kinds of quantities and qualities are said to be real, at least in a sense of res extra, a thing outside and prior to intellectual operations. However, even the members of the categories of substance, quantity and quality that correspond to real things are not theorized as such when it comes to categories: the members of the category of substance are terms that signify in a certain modus praedicandi; the same in what concerns the members of any category. So, what distinguishes categories from one another is their proper modus praedicandi, and categories are said to be uncomplex terms which are suited to be significative of subjects and predicates (Summ. in Praed. 3.1.8: 18).

With this definition in mind, Buridan argues what follows:

Et sciendum est quod nunquam Aristoteles posuit rationem ad ostendendum quod non essent alia praedicamenta praeter ista decem. Nec esset inconveniens ponere alia, si invenirentur praedicabilia habentia alios modos praedicandi, non reducibiles nec contentos sub istis modis secundum quos sumuntur haec decem praedicamenta (Summ. in Praed. 3.1.8: 18).

And we should know that Aristotle never provided an argument to show that there are no other categories besides these ten, nor would it be unacceptable to posit also others if other predicables were found that have different modes of predication, which are neither reducible to nor contained under the ones from which these ten categories are derived (transl. Klima, 2001: 151).

The reason why there are only ten genera generalissima is just inductively justified: it seems that every term that is used has one of these ten modi praedicandi, but if a term that has a different mode appears, the list could be augmented.

So, in John Buridan’s commentary, we can gather the following conclusions: 1) Buridan is not particularly interested in Petrus Hispanus’s text, but in making his own points from Aristotle and the Liber sex principiorum; 2) the categories are uncomplex terms and, as such, they should be next to the treatise on supposition, that also deals with terms; 3) what distinguishes the categories from one another is their proper modus praedicandi and so the Aristotelian list of the categories has no a priori justification.

2. John Versor

This Parisian Dominican author of the second half of the 15th century was influenced in his thought both by Thomas Aquinas and Albert the Great, but he created his own synthesis and was seen neither as a Thomist nor as an Albertist by his contemporaries (Rutten, 2005: 292-329; Geudens, 2020). From the many 15th and 16th century editions of his commentary, I will use the Venice 1572 edition of Petrus Hispanus’ Tractatus with Versor’s exposition.

Versor, as Buridan, gathers the treatises on supposition in a single treatise titled Parva logicalia. He puts this treatise at the end, after the treatise on fallacies.

Here are Versor’s titles and order of the treatises:

1) De vocibus, de nomine et verbo. De oratione et eius speciebus… (1)
2) De quinque universalibus sive praedicabilibus (2)
3) De antepraedicamentis. De decem praedicamentis. De postpraedicamentis (3)
4) De principiis syllogismi simpliciter… (4)
5) De syllogismo topico seu probabili… (5)
6) De syllogismorum multiplicitate, ac disputationum variis generibus… (7)
7) Parva logicalia (6 + 8-12).

So, the difference with the alleged original Tractatus’s order is that Versor decides to separate the properly Aristotelian treatises from the treatises about the properties of terms (a distinction between logica antiquorum and logica modernorum). Despite this, in the beginning of the treatises on supposition and the properties of terms, Versor clarifies that one should consider several possibilities linked to several uses of supposition theory:

Sciendum quod iste tractatus est utilis ad cognoscendum veritatem et falsitatem enunciationis, quia suppositio est quaedam proprietas principiorum enunciationis, ex quorum mutatione saepe variatur veritas, vel falsitas in enunciationibus. Est etiam utilis ad argumentationes sophisticas cognoscendas, et specialiter ad argumentationes fallaciae figurae dictionis, quae provenit ex diversa suppositione terminorum, unde aliqui hunc tractatum ordinant post tractatum fallaciarum, et istud communiter est in pluribus textibus. Sed melius, ut videtur, ordinandus est post tractatum praedicamentorum, quia in isto tractatu determinatur de termino incomplexo, sicut in tractatu praedicamentorum (P. Hisp. Summ. Log. Versorii Expos.: 207vE).

One should know that this treatise is useful for the knowledge of the truth and falsity of the enunciation because supposition is a certain property of the principles of enunciation: truth and falsity in enunciations varies frequently according to the change of their <principles, i.e., the terms>. It is also useful for the knowledge of sophistic argumentations, and especially for the figurae dicitionis fallacy, which arises from the diverse supposition of terms. That is why some <authors> place this treatise after the treatise on fallacies, and this is common in various texts. But it seems to be better placed after the treatise on the categories, since the uncomplex term is defined in this treatise, such as in the treatise on the categories.5

As Buridan, Versor also thinks that the treatises on supposition would be better placed after the treatise on the Categories, because they deal with the same subject: uncomplex term. But since supposition is also important for the knowledge of the truth and falsity of fallacies (especially figurae dictionis), it is correct to put it after the treatise on fallacies.

In what concerns the subject-matter of the categories, Versor follows a traditional approach that was almost a communis opinio in the second half of the 13th century. The subject-matter of the categories is the famous dicibile incomplexum ordinabile in genere secundum sub et supra. But this is the logical treatment of this subject. There are, according to Versor, two other ways of considering the categories. As the first principles of diversity of formal things (prima principia diversitatis rerum formalia), they cannot be dealt with by any science and there are not any demonstrations about them. This is a sign of their irreducibility. To fit in a science, they must not be considered by their proper formal reason, which has not got a definition (or else, they would not be genera generalissima), but as they are reduced to something common to them. They can either be reduced to being, as partes entis, and as such, they are considered in metaphysics; or they can be reduced to the uncomplex sayable (dicibile incomplexum), and in this way, referring to the ratio of being sayable and predicable, they are considered in logic. The logical treatment of the categories takes them not by themselves nor directly as parts of being, but as foundations of second intentions.6

But what is a sayable (dicibile) or a foundation of second intentions for Versor? A sayable is not a word. He is talking about things, real things, which are not being treated directly as real, but as they are used in speech. So, when he presents his justification for the Aristotelian list of categories, he creates a via divisiva through divisions of being (P. Hisp. Summ. Log. Versorii Expos.: 78bF-G), something typical from the 13th century, at least until it was criticized by authors like Olivi and, especially, Scotus. Versor does not respond to these criticisms and advocates the Thomistic and also Albertistic coincidence or isomorphism between being and predication. His sufficientia is very similar to those of Thomas, Albert, Peter of Auvergne or Simon of Faversham (Correia, 2020).

It is interesting to notice this: Versor repeats these viae divisivae or sufficientiae, and he also generally repeats positions that were very common at least in the second half of the 13th century. He does not seem very interested in finding out Petrus Hispanus’s personal position or in interpreting his text. The Tractatus is just a form or a structure to be filled with some content. It is never more than that.

Like Buridan, Versor thinks that the treatises on supposition should be next to the treatise on the Categories, but unlike Buridan, Versor keeps them separate. It is clear that categories have a place in logic in a very particular sense: as the real things that, when taken as sayable things, are the foundation of second intentions.

3. Peter Tartaret

Tartaret, a self-proclaimed Scotist, was a metaphysician and theologian at Paris at the end of the 15th century and the beginning of the 16th century (Geudens, 2020). As mentioned before, the commentary of Peter Tartaret to the Tractatus was also very widespread and it had at least 12 printed editions. Here, I will use the Venice edition of 1621, In summulas (ut vocant) Petri Hispani.

His order of the treatises is as follows:

1) Aristotelis de interpretatione (1)
2) Porphyrianas quinque voces seu (ut vocant) Praedicabilia (2)
3) Decem Aristotelis Categoriis (3)
4) Resolutorios priores Aristotelis (4)
5) Aristotelis Topicen (5)
6) Aristotelis libellum de sophisticis redargutionibus (7)
7) De suppositionibus (6)
8) De relativis (8)
9) De ampliationibus (9)
10) De restrictionibus (11)
11) De appellationibus (10)
12) De distributionibus (12)

Like Versor, Tartaret puts the treatises on the properties of terms in the end. The only thing that is different from Versor is that Tartaret changes the order of De restrictionibus and De appellationibus, maybe because it seemed more coherent to have restriction immediately after ampliation.

He does not follow Buridan and Versor’s approach of arguing for the gathering of the treatise on the Categories and the treatise on supposition. The reason behind this might be that, for him, the treatise on supposition does not have the term directly as its subject-matter, but some accidental properties that show how a term contributes to the truth or falsity of a proposition. His definition of supposition is copied from Marsilius of Inghen (cf. De Rijk, 1973: 45):

Suppositio est acceptio termini in propositione, nati accipi pro aliquo, vel aliquibus, de quo, vel de quibus, talis terminus natus est verificari, mediante copula talis propositionis (Tartaret, In Summ. Petri Hispani: ff. 125vH-126rA).

Supposition is the acceptio of the term within a proposition, naturally apt to take the place (accipi) of something, or some things, about which such a term is naturally apt to be verified by means of the copula of that proposition.

Since the 14th century it is typical for logicians to discuss supposition exclusively in a propositional context. This leads to the disappearance of suppositio naturalis (De Rijk, 1973: 46). Tartaret also takes this approach. Supposition is concerned with the truth of propositions. This is different from the way uncomplex terms are discussed in the treatise on the Categories. Tartaret considers that there are several ways of dealing with the categories. In logic, they are discussed secunde intentionaliter, that is, in respect with rationes which are attributed to things of first intention, or notitiae actuales rerum, or res cognitae. About the complicated issue of the subject-matter of Aristotle’s Categories, Tartaret refers back to the prohemium of his commentaries to logic, question 2. In this question, he argues in a Scotistic manner that the categories in logic are about the coordination of intentions, not about res, nor voces.7

What is interesting to notice is that the more complicated question is deferred to another work. Though for different reasons, in Tartaret there is no logical justification of Aristotle’s list, like in Buridan. Only Versor, who assumes a strict isomorphism between being and predication, can do a sufficientia or via divisiva of the categories.

4. Concluding remarks

The first conclusion we can gather from these three influential commentators is that the place of the treatises within the Tractatus may have changed due to a theoretical problem: how the categories are related to terms and their properties.

The second conclusion I would like to posit is that none of these commentators is very interested in Petrus Hispanus himself. They just want a background or draft from which they can organize their own thought. Finally, it is interesting to notice that authors and editions from later periods, such as Versor and Tartaret and the 16th- and 17th-century editions of their work, never attribute the Tractatus to Pope John XXI.8

Bibliography

Sources

Manuscripts

» Cordoba, Biblioteca del Cabildo, Ms. 158, ff. 30ra-72vb.

» Firenze, Biblioteca Medicea Laurenziana, Ms. Fiesolano 145, ff. 35ra-46va.

» Milano, Biblioteca Ambrosiana, Ms. H 64 inf, ff. 1ra-49vb.

» Tarragona, Arxiu Històric Arxidiocesà, Ms. 2 (85), ff. 1ra-25rb (diplomatic edition: https://scta.lombardpress.org/).

» Vaticano, Biblioteca Apostolica Vaticana, Ms. Reg. lat. 1731, ff. 1ra-29va.

Editions

» Johannes Buridanus (1994). Summulae. In Praedicamenta. Ed. Bos, E. P. Nijmigen: Ingenium Publishers (Artistarium 10-3).

» Johannes Buridanus (1998). Summulae. De suppositionibus. Ed. van der Lecq, R. Nijmigen: Ingenium Publishers (Artistarium 10-4).

» Peter of Spain (1992). Syncategoreumata. Ed. De Rijk, L. M., transl. Spruyt, J. Leiden: Brill.

» Petrus Hispanus - Johannes Versor (1572). Petri Hispani Summulae Logicales cum Versorii Parisiensis Clarissima Expositione. Ed. F. Sansovinum: Venice.

» Petrus Hispanus Portugalensis (1972). Tractatus called afterwards Summule Logicales. Ed. De Rijk, L. M. Assen: Van Gorcum.

» Petrus Tartaretus (1621). Petri Tartareti Scotistarum longe praecipui in Summulas (ut vocant) Petri Hispani de articulata, siue per capita expositio admodum luculenta. Ed. Ioannes Baptista Combus: Venice.

» Petrus Tartaretus (1621). In Aristotelis logicam et Porphyrii Isagogen eruditissimae explanationes. Ed. Iacobus Sarzina: Venice.

Translation

» John Buridan (2001). Summulae de Dialectica. Transl. Klima, G. New Haven - London: Yale University Press.

Complementary Bibliography

» Bos, E. P. (1994). “Introduction”. In: Johannes Buridanus (1994). Summulae. In Praedicamenta. Ed. Idem. Nijmigen: Ingenium Publishers (Artistarium 10-3).

» Correia, M. (2020). De sufficientia praedicamentorum: suficiência e distinção das categorias na escolástica medieval. PhD thesis, Porto: Faculdade de Letras da Universidade do Porto.

» De Rijk, L. M. (1973). “The Development of Suppositio naturalis in Mediaeval Logic. II”, Vivarium 11.1, 43-79. DOI: https://doi.org/10.1163/156853473X00026.

» Geudens, C. (2020). “Versoris, Johannes”. In: Sgarbi, M. (ed.). Encyclopedia of Renaissance Philosophy. Springer, Cham. DOI: https://doi.org/10.1007/978-3-319-02848-4_572-3.

» Geudens, C. (2020). “Tartaret, Pierre”. In: Sgarbi, M. (ed.). Encyclopedia of Renaissance Philosophy. Springer, Cham. DOI: https://doi.org/10.1007/978-3-319-02848-4_657-2.

» Maierù, A. (1994). University Training in Medieval Europe. Leiden et al.: Brill.

» Meirinhos, J. F. P. (2002). Pedro Hispano (séc. XIII). Vol. 2: …et multa scripsit. Porto: Faculdade de Letras da Universidade do Porto.

» Meirinhos, J. F. P. (2011). Bibliotheca Manuscripta Petri Hispani. Os manuscritos das obras atribuídas a Pedro Hispano. Lisbon: Fundação Calouste Gulbenkian and FCT.

» Rutten, P. (2005). “Secundum processum et mentem Versoris: John Versor and His Relation to the Schools of Thought Reconsidered”, Vivarium 43.2, 292-336. DOI: https://doi.org/10.1163/156853405774978290.

---