The Summa Iovis is not a book about (or by) Jove, nor about any of the classical mythological deities. Instead, it is a type of ars dictaminis, instructing its readers in the fine points of composing a letter. Its 107 lines provide guidance for the parts of a letter (salutatio, exordium, narratio, petitio, and conclusio), a list of stylistic and lexical faults one should avoid, and the rhetorical embellishments one should choose. The "Jove" mentioned in the title is the pseudonym of the author, of whom Lorenz--with all due academic caution--suggests that he might be Johannes de Clacy, Magister at Soissons, who died in 1308 (51), a suggestion that gains some credence by the fact that two manuscripts, albeit ostensibly through a copying error, actually attribute the "Summa" to a "Johannes."
Lorenz structures his book in four chapters which are followed by an edition and translation of the "Summa Iovis," an excerpt from Guido Faba's "Summa dictaminis," and an edition of the commentary to the "Summa Iovis." Chapter 1 defines the concept "Lehrgedicht" = didactic poem, following, in the main, Thomas Haye's magisterial definition, with slight modifications from Vivien Law and Bernhard Pabst. As Haye had so clearly shown, didactic poems manage to condense the material to be learned/memorized, sometimes to such an extent that they border on the incomprehensible. The conciseness of the poems, in turn, gives rise to sometimes extensive commentaries that are frequently transmitted with, and at times dwarf, the poems themselves. Poem and surrounding commentary thus are a necessary complement to each other: the bulk of the commentary is reduced in the poem; the conciseness of the poem is fleshed out by the commentary. The same chapter also deals with the questions of "libelli," i.e. independent quires that may at a later time have been bound together with other texts. Since the "Summa" is a short poem, it always is bound with other texts, and since it is a "didactic poem," in the last part of Chapter 1 Lorenz provides a general overview of what constitutes a school text.
Having laid the foundations, Lorenz moves to a discussion of the date and author of the "Summa" in Chapter 2. Guido Faba's "Summa dictaminis," which is thought to have been composed around 1228/1229, and on which the "Summa Iovis" relies, provides the terminus post quem. The oldest manuscript, Erfurt, Amplonianus 4° 378, provides the terminus ante quem with a date of ca. 1350. Chapter 2 also contains Lorenz's careful examination of the identity of the author, alluded to above. Even though the identification of "Jupiter" with Johannes de Clacy is tempting, Lorenz wisely leaves the time frame for the composition of the "Summa" open to the period of 1228-1350. The next part of this chapter deals with the forty-four extant manuscripts of the "Summa," which span two centuries. They are listed alphabetically. Although an alphabetical arrangement facilitates finding an individual manuscript, a chronological ordering might have been preferable, especially since the edition of the "Summa" is based on the seven earliest manuscripts (fourteenth and early fifteenth centuries), and one has to look for information on them among the other manuscripts discussed. The full content of all the manuscripts is provided, as well as origin, date, provenance, and a clear indication of whether the "Summa" is contemporary with the other texts of the manuscript or not. Lorenz also provides a brief reference to secondary sources on the manuscripts. The list contains everything one could wish for, except in one instance: Melk, Stiftsbibliothek 685 does not provide a date (though the secondary sources that are mentioned might do so), and more clarity would have been helpful for the comment "The 'Summa Iovis' was interpolated into another ars dictandi" (61). The listed contents of this manuscript are an "Opus metricum" (fols. 309r-324r) and a "De quantitate syllabarum" (fols. 324v-328v), both by Johannes Schlitpacher, and one wonders how the "Summa" and its commentary, which can be found on fols. 300r to 336v, could have been "interpolated" into these texts. The folio numbers suggest that Schlitpacher's text were instead interpolated into the "Summa." Chapter 2 also contains a superb detailed verse-by-verse examination of the poem in which Lorenz explains what is meant by each line, and in which he attempts to find the sources on which the author drew, which, other than Guido Faba, are the "Rethorica ad Herennium," Bene of Florence, Isidore of Seville, Donatus, Priscian, and others. Two more sections round out Chapter 2: the first of these examines the "Summa Iovis" as a "Lehrgedicht," and comes to the conclusion that it clearly belongs to this genre; and the final section sums up the relationship of the "Summa" to its sources.
Chapter 3 returns to the question of which other texts are bound with the "Summa." Whereas in Chapter 1 Lorenz only touched on the question, he now examines the manuscript context in detail for thirteen of the manuscripts, and more summarily for another twenty-three. After this summary examination, he turns to a single manuscript, written by the Dominican monk Albertus Löffler, of whom Lorenz can provide a fairly extensive biography as well as a list of other manuscripts he had written. Knowledge of an owner's biography as well as of his other interests would, one might assume, help to pin down the uses to which the owner put the "Summa." Unfortunately, Lorenz has to concede that the purposes for which Löffler compiled the manuscript, be they private, for his activity as a scribe, or for his activity as a teacher, cannot be determined (215).
Chapter 4 sums up the points made in the previous chapters, and returns to the question as to how the "Summa" might have been used--in the school, by a private person, or by someone tasked with official correspondence? The answer depends on the manuscript context, but even it cannot always definitively determine to which use the "Summa" was put.
An edition and translation of the "Summa," an excerpt from Guido Faba's "Summa Dictaminis," and an edition of the commentary to the "Summa Iovis" round out the volume. The excerpt from Guido Faba is partly justified by the fact that it constitutes one of the chief sources of the "Summa Iovis," though strictly speaking it is not necessary; the point that the "Summa Iovis" relies on Guido Faba has been made throughout the book and the excerpt does not greatly advance our knowledge. It could easily have been omitted. Since, according to Haye, a didactic poem and its commentary are closely interrelated, Lorenz might have printed the two together (rather than have them separated by Guido) and he might have examined the relationship between the two more closely throughout the book, especially since the commentary, even more than the manuscript context, might have provided greater clarification as to the intended uses of the "Summa." Lorenz, I hasten to add, does not ignore the commentary in the book, but does not subject it to the same detailed analysis as for instance the manuscript context.
The book could have done with somewhat more careful proofreading of both the German (e.g. "Heideberg" instead of "Heidelberg" on p. 196; or "wurde in einen andere ars dictandi interpoliert" instead of "in eine andere," p. 61; the curious date "8. August 1499233" on p. 216) and the Latin (e.g. "commenatrio" instead of "commentario" on p. 61; "in Donatem" instead of "in Donatum" on p. 62; "copiose et ornatque dicere" which should be either "copiose ornateque dicere" or "copiose et ornate dicere" on p. 116), though I have to admit to the humour of "tam in mero quam in prosa" (114)--"as much in wine as in prose," which of course should read "metro"--"as much in verse as in prose."
These minor errors aside, the book is a fine discussion of the "Summa Iovis," of its manuscript context(s), and of the uses to which the manuscripts might have been put. And even though, rightly, Lorenz does not provide a definitive answer to this latter question, his examination is exemplary.