JOHN of Cornwall (*Iohannes Cornubiensis*). — Theologian of the 12th century, d. c. 1176. Little is known of his life; even his place of origin is uncertain, so that some consider him French, others English. The only certain information is that he studied in Paris at the school of Peter Lombard, Robert of Melun, and Maurice of Sully.
Of the writings attributed to him, the *Euogium ad Alexandrum papam III, quod Christus sit aliquis homo* (PL 199,1041-86) is incontestably his, in which he combats the doctrines of Abelard, Gilbert of Poitiers, and Peter Lombard, who upheld *Christological nihilism* (according to which the humanity of Christ was but a garment of the Word) condemned at the Council of Tours in 1163.
Bibl.: J. Baudot, s. V. in DThC, VIII, cols. 756-59 (with bibliography); A. Landgraf, s. V. in LThK, V, cols. 488; F. Pelster, *Eine ungedruckte Einleitung zu einer zweiten Auflage des Eulogium*, in *Histor. Jahrb.*, 54 (1934), pp. 223-29; F. R. Studeny, *Johann of Cornwall*, an opponent of nihilism. A study in the christological controversies of the twelfth century, *Mödling* (Vienna) 1939; I. De Ghellinck, *Le mouvement théologique du XIIe siècle*, 2nd ed., Bruges 1948, pp. 253-55; A. M. Landgraf, *Einführung in die Geschichte der theologischen Literatur der Frühscholastik*, Regensburg 1948, pp. 111-12; E. Rathbone, *John of Cornwall. A brief Biography*, in *Recherches de théologie ancienne et médiévale*, 17 (1939), pp. 46-60.