Thomas Gallus, who died in 1246, spent most of his later years as abbot of St Andrew's at Vercelli in north Italy, having previously been a canon of St Victor in Paris. He is one of the foremost Victorine theologians of the twelfth and thirteenth centuries and he drew on the work of his predecessors, especially Richard. His best known work, written in 1238 and available in print, is his Extractio of the writings of Denis the pseudo-Areopagite; this is a simplified representation or ‘watering down’ of these difficult works. Gallus' other writings include a hefty commentary (Explanatio) on them (c. 1241–4) and Glosses (Glose) on the Celestial or Angelic hierarchy (written in1224), Lawell here publishes for the first time the Glose and the entire Explanatio, only part of which had appeared earlier in a publication which is ‘virtually impossible to find’ (Explanatio, p. xxix). Both works are readable, methodical, thorough and clear. Introducing the treatise on Divine names Gallus produces a plain man's guide to Denis's rarefied terminology. Throughout the Explanatio Gallus divides the text using letters and numbers to facilitate cross-referencing and he had a similar system for biblical references (e.g. Iob 39f). He did not divide the Glose in this way but Lawell has done so in order to make comparison with the Explanatio easier. Gallus made a ‘staggering number’ (Explanatio, p. xxv) of references to the Bible and to the Dionisian corpus, and Lawell's long indices to the sources that Gallus cited are admirable, as are the editions themselves in which sources and variant readings are scrupulously recorded. Gallus focussed closely and almost entirely on the texts provided by Denis and on the Bible. He seldom digressed into making an aside. He did allow himself to make very brief remarks on how sacraments used to be celebrated, on the allegory of the two swords, on the similarities between regular canons and monks, on his plan to compose questions on the Dionisian books, and on the relationship between pope and legate (Explanatio, pp. 737, 931, 942, 960; Glose, p. 94). But he did not get drawn, as did so many of his contemporaries, into controversy about the modern structure of the ecclesiastical hierarchy. Unlike the Extractio, and unlike the contemporary commentaries of Robert Grosseteste, these writings did not enjoy fame. There is only one manuscript of the Glose and only three of the complete Explanatio. Had Gallus stayed in Paris and not gone to Vercelli perhaps both would have become better known, Thanks to Lawell's achievement, they can now do so.