After studying for the academic year 1491-92 at Cambridge, Maior went to Paris where he enrolled at the Collège de Sainte-Barbe. Graduating with a master's degree in 1495 he then went to the Collège de Montaigu, one of the colleges making up the Faculty of Arts of the University of Paris. Giles Aicelin, the Archbishop of Rouen, had founded the college under the name Collège des Aicelins in 1314. Later one of his relations Pierre Aicelin de Montaigu, the Bishop of Nevers and Laon, restored the college and its name was changed at this time. Jan Standonck became Master of the College in 1483 and he filled that position when Maior began his theology studies there. In 1499 Standonck was forced to leave Paris and Noël Béda and Maior, both Standonck's students, took charge. However Maior soon left to move to the Collège de Navarre leaving Béda to maintain the position of the Collège de Montaigu as one of the leading theological colleges of Paris.
Maior became a doctor of theology in 1506, while at the Collège de Navarre. He then became a teacher at the Collège de Sorbonne, a theological college of the University of Paris founded in 1257 by Robert de Sorbon, certainly the leading theology college in Paris but perhaps the world leader at this time. The College was frequently required to give opinions on important ecclesiastical and theological issues and at the time Maior taught there it made the final decisions as whether translations of sacred texts should be accepted or banned. The time Maior spent in Paris was not only the most productive of his life, but also the most influential. He started a school there which consisted of mainly Spanish and Scottish students. A Spanish student who was a member of the school studying under Maior, wrote to the representative of the Spanish King in Paris:-
I am following the theology course of John Maior with great interest as he is a deeply knowledgeable man whose virtue is as great as his faith. ... may the eternal king deign to grant him long life that he may for long years be useful to our alma mater, the University of Paris.The Spanish members of Maior's school returned to Spain to form the "calculatores" who studied mechanics, being particularly involved with numerical examples, and using as their main tools the elements of proportion theory and infinitesimal arithmetic. Lax was a student of Maior in Paris, who returned to Spain to be a leading calculatores.
Maior also had an outstanding reputation as a prolific author and an outstanding teacher. In 1518, when at the height of his fame in Paris, he returned to Scotland. He had written in a text a few years earlier:-
Our native soil attracts us with a secret and inexpressible sweetness and does not permit us to forget it.In fact Maior returned to Scotland to become principal of Glasgow University. Was he attracted back not only to his native soil but also to his alma mater? During this period he wrote Historia Majoris Britanniae tam Angliae quam Scotiae (History of Greater Britain, England and Scotland). Of course 'Historia Majoris' is a pun on Maior's History. During this time he was also a canon of the Chapel Royal at Stirling, and a priest at Dunlop in Ayrshire. In June 1523 Maior took up an appointment at the University of St Andrews. He lectured both to theology students and to arts students, giving couses on logic to the latter group of students. He also held important administrative roles, being assessor to the Dean of Arts. In this capacity he served on a committee which revised the examination system at St Andrews, giving it a similar structure to that of Paris.
If Scotland had attracted him back when in Paris, now that he had spent eight years in Scotland he was attracted back to Paris. Returning in 1526 he seems to have wanted to become fully involved in teaching again and indeed he took up his teaching career in Paris much where he had left it eight years earlier. After five years teaching in Paris, Maior returned again to Scotland and in particular to St Andrews. He again took up major administrative roles being provost of St Salvator's College from 1534 and Dean of the Faculty of Theology. He continued to tutor, however, and one of the students he taught during this period was John Knox, the main instigator of the Reformation in Scotland. Knox wrote that Maior was a man:-
... whose word was then held as an oracle on matters of religion.Rather strangely Maior had also taught John Calvin, who became the leading French Protestant Reformer, during his second spell in Paris. Certainly the fact that Maior taught two major Protestant Reformers should not make one think that Maior was anything but totally conservative on Roman Catholic doctrine. On the other hand this did not mean that he was not critical of those in the Church. He spoke out strongly in favour of proper treatment of American Indians, and included in his writings a proper moral theological framework for such treatment. He condemned the way many priests neglected their duty of care, he condemned priests who were always absent from the parish they were appointed to, he condemned the 'grasping abbots', and most of all he condemned corruption in the Church:-
They deceive themselves who think that the approval of even the supreme pontiff can reconcile such things to the dictates of conscience.He was interested in mathematics and logic and applied these to physics, writing an important text on the infinite Propositum de infinito in 1506 :-
... in which he argues in favour of the existence of actual infinities and discusses the possibility of motion od an infinite body.Maior was also influential in spreading the work of Bradwardine and Swineshead in his teaching :-
Maior's importance for physical science derives from his interest in logic and mathematics and their application to the problems of natural philosophy. He became an important avenue through which the writings of the fourteenth-century Mertonians, especially Bradwardine, Heytesbury, and Swineshead, exerted an influence in the schools of the sixteenth century, including those at Padua and Pisa, where the young Galileo received his education.Maior wrote important commentaries on works of Aristotle. In his commentary of the Ethics, he wrote:-
In almost all opinions he agrees with the catholic and truest Christian faith in all its integrity ... in so great and manifold a work [as the Ethics] if it be read as we explain it, you meet scarcely a single opinion unworthy of a Christian gentlemen.Broadie in  ends his article with these words:-
By the time Maior died, in 1550, just ten years before the Reformation in Scotland, he must have known that the world to which he had dedicated his life was gone for ever.
Article by: J J O'Connor and E F Robertson