After joining the Dominican Order, he studied and taught at Padua, Bologna, Cologne and other German convents in Hildesheim, Freiburg, Ratisbon, Strasbourg, and Cologne. He was sent to the Dominican convent of Saint-Jacques at the University of Paris in about 1241 where he read the new translations, with commentaries, of the Arabic and Greek texts of Aristotle. This was a period when the writings of Arabic scholars, and through them the texts of ancient Greek philosophers, was becoming known throughout Christian Europe and it was having to come to terms with this new knowledge. Albertus would play a major role in accepting this new learning into Europe with his wide ranging scholarship over essentially the whole of knowledge.
He taught for four years at Saint-Jacques, giving courses on the Bible and on the theological textbook The Book of the Sentences which had been written by Peter Lombard. In 1245 he received the degree of Master of Theology from the University of Paris and, after receiving this degree, one of the first students he taught was Thomas Aquinas. While in Paris Albertus began the task of presenting the entire body of knowledge, natural science, logic, rhetoric, mathematics, astronomy, ethics, economics, politics and metaphysics. He wrote commentaries on the Bible, Peter Lombard's Book of the Sentences, and all of Aristotle's works. These commentaries contained his own observations and experiments. By 'experiment' Albertus meant 'observing, describing and classifying'. For example, in De Mineralibus Albertus wrote:-
The aim of natural science is not simply to accept the statements of others, but to investigate the causes that are at work in nature.We should not underestimate the importance of such ideas, for most scholars at that time believed that knowledge could only be obtained from a study of the scriptures. In the 13th century few were prepared to even consider the possibility of scientific research, and most considered that knowledge all came from God through ancient divinely inspired writings. Not only did Albertus advocate what we would call today the scientific approach to studying the real world, but he did so in such a way that his ideas were accepted by the Church. Again in a work on plants Albertus wrote:-
In studying nature we have not to inquire how God the Creator may, as He freely wills, use His creatures to work miracles and thereby show forth His power: we have rather to inquire what Nature with its immanent causes can naturally bring to pass.These quotes show that, although he did an immense amount of valuable work in collecting and propagating the ideas of earlier scientists in his numerous and wide ranging writings, he also saw the value of new research by experiment. Not everyone held Albertus in high esteem, however. Bacon, who was a contemporary, and in many ways a rival of Albertus, was highly critical (although one can sense that he is attacking someone who he considers to have undeservedly achieved more than he has). Bacon writes that Albertus:-
... is a man of infinite patience and has amassed great information, but his works have four faults. The first is boundless, puerile vanity; the second in ineffable falsity; the third is superfluity of bulk; and the fourth is his ignorance of the most useful and the most beautiful parts of philosophy.One has to understand that Bacon was himself an even stronger advocate of experimental science than was Albertus but, although himself a devote Christian, unlike Albertus he overstepped what the Church might accept. Bacon was also correct to see errors in Albertus's writings for Bacon had a deeper understanding of science than had Albertus.
In 1248 Albertus left Paris to set up the new Studium Generale which was essentially a Dominican university in Cologne. He was Regent of the Studium Generale from the time that he set it up until 1254 and during this time he lectured, wrote important works, and worked closely with his student Thomas Aquinas who was appointed Master of Students (at least until 1252 when Aquinas returned to Paris). In 1254 Albertus became superior of the Dominican province of Teutonia (Germany). He now had a heavy administrative load but still found time to continue his scientific work. However, wishing to spend still more time on scientific work, he resigned from his role of Provincial in 1257 and returned to Cologne.
In 1260 he was appointed Bishop of Ratisbon despite the efforts of Humbert de Romanis, the Head of the Dominican Order, to keep Magnus within the Order. After two years he resigned as bishop and returned to his position as professor at the Studium Generale in Cologne. In 1274 Pope Gregory X required Albertus to attend the Second Council of Lyon. At this Roman Catholic Council Albertus took a full part in discussing questions of doctrine, administration, discipline, and other matters. Thomas Aquinas died in 1274 (actually on his way to the Council in Lyon) and three years later certain factions within the Church tried to condemn his teachings on the grounds that he was too favourably disposed to non-Christian philosophers, both Arabic and Greek. By this time Albertus was an old man, but he travelled to Paris to argue in favour of Thomas Aquinas, whose ideas of course, although not identical to his own, were similar in their support for the teachings of Aristotle.
We should note, however, that Albertus did not treat Aristotle's writings as absolutely and necessarily correct. He stated:-
Whoever believes that Aristotle was a god, must also believe that he never erred. But if one believes that Aristotle was a man, then doubtless he was liable to error just as we are.In Summa theologiae he argues for reconciling the teachings of Aristotle with Christian thinking, but nevertheless, devotes a chapter to what he calls "the errors of Aristotle".
What of Albertus's contributions to mathematics? In  Anthony Lo Bello gives:-
... an English translation, with mathematical and philosophical notes, of three sections of the commentary by Albertus Magnus on Euclid's Elements : (1) the prologue, (2) the question "Is an angle a quantity?" and (3) Book I, Proposition 11.In  J E Hofmann examines a manuscript in the Dominikaner-Bibliothek Vienna which contains a treatment of the books I to IV of Euclid's Elements in Latin by Albertus. The text shows that Albertus was familiar with the Latin translations from Arabic of Euclid's Elements by Boethius and Adelard of Bath. Since Albertus has clearly not read the translation by Campanus then, given the range of Albertus's scholarship, one can reasonably assume that Albertus wrote his commentary on Euclid before that of Campanus.
In Super Dionysii epistulas Albertus considers the motion of the "Sphere of Stars" with the aim of determining whether the eclipse at the crucifixion of Jesus of Nazareth was natural or miraculous. His methods of tracing back the positions of the sun and moon is interesting. The methods used by Albertus are examined in detail in .
Among his other works is De natura locorum (on the nature of places) which is a work on geography in which Albertus presents data on locations and features and emphasises the importance of geography in understanding the world.
Although Albertus was able to argue convincingly for Thomas Aquinas in 1277, by the following year his memory was beginning to fail him. Over the next three years he rapidly declined both mentally and physically
Albertus was made a Saint and declared a Holy Doctor of the Church on 16 December 1931 and his feast day is 15 November in each year. In 1941 Albertus was made patron of natural scientists by Pope Pius XII.
Article by: J J O'Connor and E F Robertson