Alcuin's treatise on the Trinity has the merit of brevity (three books containing sixty-one chapters) though it did not resolve the Trinitarian issues which preoccupied the more subtle minds of Gottschalk or Abelard. The work is an assemblage of excerpts, chiefly from Augustine's De Trinitate but also using Fulgentius and Marius Victorinus.Footnote ¹ The editors of this authoritative version of the text suggest that Alcuin was writing a handbook for adult catechumens, although there is evidence that their needs were often met by more elementary expositions of the Creed.Footnote ² (That it was written for Saxon converts may be doubted, though a Salzburg copy has a handful of ninth-century Old High German glosses.) The work was dedicated to Charlemagne, and it circulated rapidly across his empire and is now found in a hundred manuscripts (p. viii) and a large number of printed editions (pp. lxix–lxx). It frequently circulated not only with the set of twenty-eight questions on the Trinity edited here, but with works by Gennadius and Fortunatus. It also circulated with Alcuin's work on the soul and the editors follow Donald Bullough in seeing that grouping as the work of the Tours scriptorium. (The edition is rightly dedicated ‘ to the memory of Donald Bullough, surely Alcuin's best friend in the twentieth century’.

The present edition reports the readings of thirty-eight manuscripts, which are grouped into six hyparchetypes, the last of which represents an authorial revision of the text. Thirty manuscripts date from the ninth century, and eleven of those from the first quarter of that century. Alcuin was the Carolingian best-seller; no other ninth century author was so widely copied. Since several of the manuscripts in Munich, Paris, St Gall, Valenciennes and WolfenbuettelFootnote ³ may now be viewed online, anyone who wishes to read the text at no charge only requires internet access. My sample collations of passages at the start and the end of the work with Frobenius Forster's great 1777 edition of Alcuin did not reveal any substantial alterations to Forster's text.

Though Gottschalk quoted extensively from Alcuin's work accused him of departing from the teachings of Alcuin in his analysis of divine agency. But to refute Gottschalk Hincmar had to read Augustine and Boethius (His manuscript, Reims 390, has been fully digitides.) Carolingian copies of Augustine's De Trinitate survive from Meaux, St Germain, Ivrea, Laon, St Hubert, Fleury, Wurzburg, Echternach, Tours, St Gall, Lorsch and St Amand, often with important marginal notes which await study. The move from Alcuin back to Augustine, and the reception of Hilary of Poitiers and Boethius, was taken by far fewer Carolingian thinkers than those who read Alcuin or repeated the Trinitarian formulae of universal or provincial church councils. This expert edition reminds us that Alcuin was the friend of Charlemagne because he could guide his master into the kingdom of heaven, and that his understanding of the more incredible Christian doctrines was more influential than any number of his letters or even his verses. It is good that Alcuin's twenty-first-century friends know where to start.