IRNERIO. — Bolognese jurist (12th–13th c.). From him, with the Studium of Bologna and the school of the glossators, began the entire renewal of studies aimed at giving a second life to Roman law and laying the doctrinal foundations of common law.
Scant information survives regarding I.’s life. Thirteen documents dating from 1112 to 1125 show him as an advocate, then as a judge whose learning was sought by, among others, Countess Matilda and Emperor Henry V. The identification of I. with a namesake *missus domini imperatoris* recorded in 1100 is unlikely; any attempt to date his life and activity beyond the indicated limits belongs to the realm of hypothesis.
According to traditions reported a century later by the chronicler Burkhard of Ursberg and the glossator Odofredus, I., initially a *magister in artibus*, later turned to legal studies and, at the urging of Countess Matilda, restored to their pristine state the texts of Justinianic law, theretofore neglected: *primus illuminator scientiae nostrae* (thus Odofredus). He soon eclipsed the fame of his only predecessor, Pepo, and by his teaching drew to Bologna the large body of students that, even in his lifetime, earned the city the epithet *docta*.
Of the writings attributed to I., only the glosses on the *Corpus iuris civilis*—and not all of them—are certainly his. Some of these glosses are included in the great apparatus of Accursius, others are cited by other jurists or preserved separately in manuscripts long overlooked. Secure attribution is often hindered by the variety of sigla marking the glosses in the manuscripts, sigla corresponding to the different forms in which the name appears. The sigla G., Gar., Garn., Girn., Guar., Guarn., Var., War. belong to the original form *Guarniero*; to the later form I., whose relationship to the former has been variously explained, belong Hyr., I., Ir., Y., Yr., though not all of these can be definitively excluded from I. While he was not, as tradition mistakenly asserted, the first to gloss Roman texts, he was the one who extended this method of instruction to all parts of the *Corpus iuris*, which he reconstituted in its ancient unity thanks to the recovery of the *Infortiatum* (Dig. II.XXIV–XXXVIII) and replaced the epitomes then in vogue in the early Middle Ages; above all, he was the first to delve deeply into the legal content of those texts.
I. also played an important role in the analysis of the so-called *Authenticae*, extracts of Justinianic novellae inserted into the Code at appropriate points.
It is known that I. wrote other works, and more substantial ones: a formulary for notaries, a collection of *quaestiones*, and a treatise *De actionibus*; all are now lost. The attributions to him of the *Summa Infortiati*, the *Brachylogus*, the *Epitome exactis regibus*, the *Formularium tabellionum*, the *Quaestiones de iuris subtilitatibus*, the *De aequitate*, the *Qui de re pecuniaria*, the *Summa legis Langobardorum*, the *Summa codicis Trecensis*, the *Summa institutionum Vindobonensis*, the *Liber divinarum sententiarum*, are today generally rejected by scholarship; they stem from the desire to give more concrete form to the almost legendary figure who was called the *lucerna iuris*.