Peter of Ireland, Teacher of Aquinas

The first biographies of Thomas Aquinas, the immensely influential philosopher and theologian, were written about forty years after his death. In the first (by William of Tocco) it is said that Aquinas was educated at Naples in grammar and logic by Master Martin and in natural philosophy by “Petrus de Ibernia” ie. Peter of Ireland. In the second (by Peter Calo), Aquinas is said to have quickly learnt all that Master Martin could teach him in grammar, leading to his transfer to Master Peter the Irishman who taught him logic and natural philosophy.

This would have been in the time period 1239-44. So who was this Irish teacher of Thomas Aquinas?

Research done in the eighteenth century (by a Dominican Bernardo Rossi de Rubeis) found two potential candidates in Naples at the right time. One, called Magistro Petro de Hybernia, has been excluded by later research, but the second, a Benedictine monk named Petrus de Donis and described as Ultonienis remains a possibility. This man might be the same as a Petrus de Dunis, a member of the Benedictine community of Down, founded about 1177-78 by John de Courcy who brought Anglo-Norman monks there from Chester.

However, we have no evidence that Peter of Ireland was present in the 1240s and he is not mentioned in early accounts of Aquinas. But there seems to be little reason for William of Tocco to invent a story that Martin and Peter taught Aquinas. It is neither colourful nor likely to inflate Aquinas’ standing, and it is information Tocco could have heard it from Aquinas himself.

At this distance it seems very unlikely we can ever know if Petrus de Donis was Peter of Ireland, but we can establish one thing based on the name alone. Peter of Ireland was probably Anglo-Norman, since Peter was not used as a name by the Gaelic population. It is also unlikely that an Irish man of Gaelic race at that time would have had a career that would take him abroad for his university education, most likely to Oxford (there was no Irish university), and from there to Paris and Naples. Peter of Ireland’s presence in the Sicilian court is interesting in its own right; it is plausible he had some connections with Normans in Sicily.

There are three works extant attributed to Peter of Ireland and judged authentic: Determinatio magistralis and two commentaries on Aristotle, the great inspiration of Aquinas, all from the 1250s or 1260s.

The Determinatio magistralis was aimed at answering a question of King Manfred’s, as to whether the bodily organs are made to fulfil their functions or whether the functions happen because of the organs. King Manfred (1232-1266) was the King of Sicily from 1258, and son of the founder of the University of Naples, the emperor of the Holy Roman Empire, Frederick II. We are told that the solution (based on the first option) was given by Peter of Ireland:

He said that the problem was metaphysical rather than scientific and that its solution was to be found in Book XII of the Metaphysics and that related to the care of the First Cause regarding those things which are in the universe because it is not proper for the Wise and Omnipotent One to tolerate evil or to act unjustly but rather to arrange everything in the best way through which everything can be preserved in respect of the eternal permanency of the universe.

Peter goes on to give supporting examples from hunting birds, a source likely to appeal to Manfred who was at the time preparing a new edition of his father Frederick II’s book on falconry, De Arte Venandi cum Avibu (“The Art of Hunting with Birds”).

Frederick’s book drew on Historia animalium, a zoological natural history text by Aristotle with commentaries by Ibn Rushd (Averroes). This work had been translated by Michael Scotus, a Scottish scholar who was in Frederick’s court from around 1227. Michael had been a translator in Toledo and in 1223 had refused the nomination to become bishop of Cashel. In Frederick II’s court Michael Scotus supervised new translations from Arabic into Latin of Aristotle and of Arabian commentaries, and with Jacob ben Abba Mari Anatoli translated Maimonides’ Guide for the Perplexed. There were a huge amount of Aristotelian translations and commentaries available in Latin which Peter of Ireland could have drawn from.

As well as his written works, Peter of Ireland was also part of a Jewish-Christian group in the 1250s which studied the thought of Moses Maimonides. The Jewish scholar Moses of Salerno records two of his comments. One of them, in his Commentary on the Guide relates to the multiple meanings of possibility:

This is what the wise Christian Master Peter of Ireland has explained to me. He said that ‘possible’ can be predicated with two meanings. The first: everything can be or can not be. It is possible that in the month of Shevat that it will rain, but it is also possible that it will not. The other sense of ‘possible’ follows on from necessity. For example, Aristotle says that the world, inasmuch as it is, was possible and not impossible. Existing it is possible, inasmuch as if it were impossible, it would not have been.

The other appears in Objections, a work against the doctrine of the Trinity:

… indeed, Master Peter of Ireland accepts that Christians in believing that the Divinity has become incarnate accept the necessary conclusion that the Name has undergone passion, movement and change.

It was not only Moses of Salerno who used Peter of Ireland’s words in his works. Thomas Aquinas, whether taught by Peter or not, at the end of his life used Peter’s commentary on the Peryermenias in his project to comment on all the works of Aristotle.

Lacking a picture of Peter of Ireland, here is a self-portrait by Matthew of Paris (1200–59), a Benedictine scholar. Featured Image: Lacking a picture of Peter of Ireland, here is a self-portrait by Matthew of Paris (1200–59), a Benedictine scholar. Public domain courtesy of the British Library


All quotes and information on Peter of Ireland from:

Dunne, Michael (2006) Peter of Ireland, The University of Naples and Thomas Aquinas’ Early Education. Yearbook of the Irish Philosophical Society 2006 . pp. 84-96. Available on NUIM ePrints.

Information on Michael Scotus from St Andrews: Michael Scot.

A later writer thought Michael Scotus might have been Irish; more on the unfortunate confusion of Irish and Scottish medieval scholars here.

Mention of the translation project in the Sicilian Court here, in the History of Philosophy without any gaps.

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