The Summa Grammatica^{[n 1]} (Latin for "Overview of Grammar"; c. AD 1240^[2] or c. 1250)^[3] was one of the earlier works on Latin grammar and Aristotelian logic by the medieval English philosopher Roger Bacon.^[4] It is primarily noteworthy for its exposition of a kind of universal grammar.^[2]

The work is apparently a series of lectures given by Bacon for the mandatory classes on Priscian's work On Construction (Books XVII & XVIII of his Institutes of Grammar) at the University of Paris,^[5] where he taught in the 1230s and '40s. Much more than Bacon's later linguistic works, the Summa Grammatica lies in the mainstream of 13th-century analysis.^[3] The first part borrows directly from Robert Kilwardby's commentary on Priscian.^[6][7] More generally, the work reflects the speculative grammar taught at Oxford in such 13th-century works as the Logica cum Sit Nostra.^[8] It is probable that the final draft of the work which Bacon mentions in his Communia Naturalium^[9] was never completed.^[10] His Greek and Hebrew Grammars and Compendium of Philosophy may have been considered as part of it.^[10]

It survived in two manuscripts: P and W. P is a copy in book hand evidently intended for a personal library.^[11] W is a students' copy written in the informal hand of the late 13th or early 14th century.^[5][12]

The work describes figurative language, rhetorical devices, and irregular Latin grammar^[13] using "sophisms" or illustrative examples.^[14] It aims to complement Bacon's students' required readings of Priscian's work On Construction by presenting its important points in a more thorough and logical order.^[14] It assumes a mastery of standard grammatical rules which the students would have already learnt as glomerelli.^[15] It most frequently cites Priscian, but more often adopts the solutions of Peter Helias.^[15]

The first section lays out rules regarding grammatical agreement and the rhetorical devices antithesis,^[16][17] synthesis,^[18][19] procatalepsis,^[20][21][8] From the Aristotelian notion that "art imitates nature to the extent that it can"^[22][23] and under the influence of Averroës's commentaries,^[8] Bacon argues that nouns and pronouns can be distinguished from verbs and adverbs owing to the distinction between permanent and successive things.^[8] Further, verbs constitute a kind of movement from the subject^{[n 2]} to the object^{[24][n 3]} which imposes obligations on the grammar.^[8] For instance, owing to their origin from verbs, Bacon considers that participles and infinitives are too unstable to function properly as the object of a sentence, as "nothing which is in motion can come to rest in something in motion, no motion being able to complete itself in something in motion".^[8]

The second section deals with non-figurative constructions including impersonals,^[25][26] gerundives,^[27][28] interjections,^[29][30] and ablative absolutes.^[31][32][8]

The third section^[33] covers illustrative examples by topic in greater or less detail^[8] and more or less at random.^[34] The primary ones are Moris erat Persis ducibus tunc temporis omnem ducere in arma domum,^[35] Vestes quas geritis sordida lana fuit,^[36] Amatus sum vel fui,^[37] Vado Romam que est pulcra civitas,^[38] Video centum homines uno minus,^[39] Lupus est in fabula,^[40] In nostro magistro habet bonum hominem,^[41] Margarita est pulcherrimus lapidum,^[42] Quid nisi secrete leserunt Philide silve,^[43] and Nominativo hic magister.^[44] Most of these examples appear in other collections.^[34]

The fourth section analyses short sentences, along with adverbial phrases and liturgical formulas^[8] such as ite missa est^[45] whose use of ellipsis presented certain problems.^[34] It's divided into three sections on "On Some Cases in the Nominal Absolute",^[46][47] "On Mediate Apposition",^[48][49] and "On Some Difficulties in Speech".^[50][51]

Bacon emphasizes that grammatical rules cannot be applied mechanistically but must be understood as a structure through which to attempt to understand the author's intent (intentio proferentis).^[8] The desire to communicate some particular idea may require breaking some of the standard rules.^[52] Such exceptions must, however, be linguistically justified.^[8] In this he follows Kilwardby.^[8] Although Bacon considered an understanding of logic to be important for clarity in philosophical and theological texts, he found his era's Modist analyses needed to be tempered by a contextual understanding of the linguistic ambiguity inevitable in the imposition of signs and from the shifts of meaning and emphasis over time.^[8]

Bacon argues for a universal grammar underlying all human languages.^[2] As more tersely stated in his later Greek Grammar:^[2]

Grammar is one and the same in all languages, substantially, though it may vary, accidentally, in each of them.^{[55][n 4]}

Hovdhaugen leaves open the possibility, however, that, unlike the Modists who followed Bacon, his own statements on the subject did not refer to a universal grammar but to a universal science to be employed in studying linguistics across languages.^[56] This derives from an ambiguity in the Latin grammatica, which referred variously to the structure of language, to its description, and to the science underlying such descriptions.^[56]

• Modistae, the philosophical school which developed partially under the influence of this work^[2]
• Book III of the Opus Majus

• Bacon, Roger (1902), Nolan, Edmond; et al. (eds.), Grammatica Graeca [Greek Grammar], Cambridge: Cambridge University Press.
• Bacon, Roger (1940), Steele, Robert (ed.), Summa Gramatica necnon Sumule Dialectices, Opera Hactenus Inedita Rogeri Baconi, No. XV, Oxford: John Jonson for the Clarendon Press. (in Latin)

• "Roger Bacon", The Worthies of the United Kingdom; or Biographical Accounts of the Lives of the Most Illustrious Men, in Arts, Arms, Literature, and Science, connected with Great Britain, London: D. Sidney for Knight & Lacey, 1828, pp. 39–48.
• "Roger Bacon", Stanford Encyclopedia of Philosophy, Stanford University, 2013.
• Hovdhaugen, Eva (1990), "Una et Eadem: Some Observations on Roger Bacon's Greek Grammar", De Ortu Grammaticae: Studies in Medieval Grammar and Linguistic Theory in Memory of Jan Pinborg, Amsterdam Studies in the Theory and History of Linguistic Science, Ser. III: Studies in the History of the Language Sciences, No. 43, Amsterdam: John Benjamins Publishing, pp. 117–132, ISBN 90-272-4526-6.
• Murphy, James J. (1974), Rhetoric in the Middle Ages: A History of Rhetorical Theory from St. Augustine to the Renaissance, Berkeley: University of California Press, ISBN 0-520-04406-1.
• Rosier-Catach, Irène (1994), La Parole Comme Acte: Sur la Grammaire et la Sémantique au XIIIe Siècle, Paris: J. Vrin. (in French)
• Rosier-Catach, Irène (1997), "Roger Bacon and Grammar", Roger Bacon and the Sciences: Commemorative Essays, Studien und Texte zur Geistesgeschichte des Mittelalters, No. 57, Leiden: Brill, pp. 67–102, ISBN 90-04-10015-6.