The first Italian epic poem, the Teseida was written in response to Dante’s observation in the De vulgari eloquentia (2.2): while Cino da Pistoia had written Italian poetry about falling in love (amoris accensio) and Dante himself had made moral rectitude (directio voluntatis) the subject of his Commedia, a vernacular work on valor in arms (armorum probitas) had yet to be written. Boccaccio accepted Dante’s challenge and, in his envoy to the Teseida (12.84), expresses great hopes for his modern version of a classical epic. Contending that the Teseida represents the type of literary epic that Dante had described, Boccaccio characterizes his epic as the first to sing of the affairs of Mars «nel volgar lazio più mai non veduti» (12.84.8). The Teseida, he thus implies, is a vernacular work worthy of standing with the great achievements of Cino and of Dante.
The 9904-line poem, whose length approximates that of the Aeneid, is, like Vergil’s epic, divided into 12 books. Acknowledging the poetry of his own age, Boccaccio uses 15 sonnets, in a variety of formats, to introduce the poem and its 12 books and to conclude the poem. Some 1,300 glosses – from one word to more than 5,000 words in length – appear in the margins or between the lines of the poem.
The Teseida consists of a prose introduction in which the author states that the purpose of his poem is to win back the affection of an idealized woman whom he calls Fiammetta. Written in ottava rima, the form that also served Boccaccio in the Filostrato and the Ninfale Fiesolano, the 12-book poem narrates two related tales of love and conflict: the Athenian siege of the Amazon capital, concluding with Theseus and his men marrying the Amazon women, and the conflict between the two cousins, Palemone and Arcita, for the love of Emilia, concluding with her marriage to Arcita and, after his death, to Palemone. In each instance, the wise and model ruler, Teseo, duke of Athens, uses married love as a means to re-establish peace and to restore order. Two sonnets conclude the poem: the first asks the Muses’ blessing on the poem, requesting that they consult with his beloved lady about supplying its name; the second is the Muses’ reply, which quotes Fiammetta’s response to the poem – «Hay, quante d’amor forze in costor foro!» – and then provides the name that she and the Muses have given the poem: Theseyda di nozze d’Emilia.