Irnerius was an Italian jurist, and founder of the School of Glossators.
Irnerius was among the first scholars to write such “glosses” on Roman law, a practice from which the name of his school, “glossators,” was derived.
This kind of interpretation has been excepted by scientists as glossirovation of the text, which is writing the new text-interpretation in the margins of the main text. It was the main technique in the Irnerio’s School of glossators.
He was the author of “Summa Codicis” - the first systematic exposition of Roman law produced in the Middle Ages.
Irnerius' interlinear glosses on Justinian's code, “The Corpus Juris Civilis”, - his “Summa Codicis”, stands at the beginnings of a European law that was written, systematic, comprehensive and rational, and based on Roman law.
After Irnerius mastered the difficult text and gained a reputation as a glossator, he began teaching students law at Bologna around 1087.
The recovery and revival of Roman law, taught first at Bologna was a momentous event in European cultural history.
Irnerius worked under the patronage of Countess Matilda of Tuscany. Together with Irnerius, she is said to have help found the University of Bologna, whose faculty initially only taught law.
Irnerius was largely forgotten; his name was revived by German historians of the later 19th century.
Irnerius’s successors recognized his contribution to the disciplined study of law and honored him with the epithet lucerna juris (lamp or lantern of the law) or lumen legum (light of the law).
Glosses, originally were meagre interlinear elucidations of the text. But since the glosses were often too extensive to be inserted between the lines of the text, he began to write them on the margin of the page.
At the instance of Matilda of Canossa, countess of Tuscany, he began to devote himself to the study of jurisprudence, taking the Justinian code as a guide. It is probable that for a time he frequented a law school in Rome.
He is believed to have delivered his first law lectures at Bologna between 1084 and 1088 and to have taught Bulgarus, the most prominent of the second generation of Bolognese glossators.
After teaching jurisprudence for a short while in Rome he returned to Bologna, where he founded a new school of jurisprudence in 1084 or 1088, which would rival the law school of Ravenna.
After 1116 Countess Matilda of Tuscany employed him on diplomatic missions, as did the Holy Roman emperor Henry V. Irnerius died, perhaps during the reign of the emperor Lothair II, but certainly before 1140.
There is nothing known about his personal life.