Daβ Johannes von Salisbury in seinem zwischen 1156 und 1159 verfaβten Policraticus römisches, aber auch kirchliches Recht verwertet hat, ist in der Forschung häufig herausgestellt worden. In welch breitem Umfang dies vor allem für das römische Recht geschah, macht bereits ein kurzer Blick in den kritischen Apparat oder in den Autorenindex der Webb’schen Policraticus-Ausgabe deutlich.

Seit Savignys Geschichte des römischen Rechts im Mittelalter bewundert die Rechtswissenschaft und mit ihr die historische Forschung die Kenntnisse des Johannes von Salisbury im römischen Recht. Der groβe Forscher konnte nur den Magister Vacarius als Vermittler vermuten. Hermann Fitting hat dann bei seinen weitgespannten und irregeleiteten QueUenstudien auf ein Werk der Glossatoren aufmerksam gemacht, die sog. Summa Codicis Trecensis, die Johannes in seinem 1159 vollendeten Policraticus benutzt haben soll.

Hospitem meum Placentinum dixisse recolo, virum utrique sanguine generosum, habentem prudentiam mundi huius in timore Domini, hoc in civitatibus Italiae usu frequenti celeberrimum esse, quod, dum pacem diligunt et iustitiam colunt et periuriis abstinent, tantae libertatis et pacis gaudio perfruuntur, quod nichil est omnino, quod vel in minimo quietem eorum concutiat. Cum vero prolabuntur ad fraudes et per varias iniustitiae semitas scinduntur in semet ipsis, statim vel fastum Romanum vel furorem Teutonicum aliudve flagellum inducit Dominus super eos, et permanet manus eius extenta, donee ipsi ab iniquitate per penitentiam revertantur; quo solo remedio apud illos omnis cessat tempestas. Adiciebat etiam, quod merita populi omnem evacuant principatum aut eum faciunt esse mitissimum, cum e contrario certum sit, quod propter peccata populi permittit Deus regnare hypocritam et impossible esse, ut diu regno gaudeat qui populi humiliatione et proprio fastigio superbe nimis exultat. Sed illius dicebat protendi principatum, qui apud se de conscientia humilitatis semper in se agitur, quasi regnet invitus. Haec mihi Placentinus hospes; et, ut credo, fidei consentaneum est’.

One of the very noticeable features of John of Salisbury’s later letters is the frequency with which they refer to the affairs of the empire and its ruler Frederick Barbarossa; indeed, they are an important source for the history of the empire in the 1160s. There is no mystery about why this should have been so. The papal schism which broke out in 1159 and which was sustained by Barbarossa was of great importance for John and his circle, both in itself as a matter of great concern to those who cared about the church, and in particular because its progress often affected the course of the dispute between Becket and Henry II.

Johannes Sarebiriensis, quondam clericus beati Thomae martiris, diuina dignatione et meritis beati Thomae martiris, Carnotensis ecclesiae minister humilis’. This protocol from the last known letter to come from John of Salisbury’s hand attests his continuing devotion to the memory of the blessed martyr of Canterbury and his pride in having once belonged to his household. John had made an important contribution to the beginning of the cult of Saint Thomas the Martyr.

No single manuscript containing both the major collections of John of Salisbury’s letters is known to survive, but it seems possible to establish that such a manuscript once existed from the evidence of a fourteenth-century tabula found in Durham Cathedral Library MS A.IV.8 fols 53-9. There is no indication of when or how this tabula came to Durham; the composite manuscript of which it forms part was not assembled in its present form until after 1500, when the last section was still separate. The tabula contains some four hundred quotations arranged under 235 subject headings running in alphabetical order from Absencia to Penitencia; the remainder is missing. Almost every entry consists of a quotation, a number in arabic numerals, a name or personal title in the dative case or with ad and the accusative, and a brief indication of position; so for example under the heading Exulare the one entry runs bis exulat qui domi exulat 387 archidiacono exon prope finem. The quotations are from letters in John of Salisbury’s collections or from the other Becket correspondence.