Exploring intertextuality across the H omeric poems through language models (2024)

Abstract: Past research has modelled statistically the language of the Homeric poems, assessing the degree of surprisal for each verse through diverse metrics and resulting to the HoLM resource. In this study we utilise the HoLM resource to explore cross poem affinity at the verse level, looking at Iliadic verses and passages that are less surprising to the Odyssean model than to the Iliadic one and vice-versa. Using the same tool, we investigate verses that evoke greater surprise when assessed by a local model trained solely on their source book, compared to a global model trained on the entire source poem. Investigating deeper on the distribution of such verses across the Homeric poems we employ machine learning text classification to further analyse quantitatively cross-poem affinity in selected books.

## background the precise process by which the monumental ancient greek epics, the iliad and the odyssey, came into being remains a point of speculation. that they have survived to the present day may be traced back to the hellenistic period of ancient greece (c. 330 bce), when early scholars focused on issues of textualisation, primarily editing, in order to curate the canonical version of homer. less clear is how the poems arrived at this point. though ever more detailed and in-depth references to them had been occurring over the previous two centuries, there is no documentation relating to the moment of their composition, primarily because they were the product of a vibrant oral society. rather than being seen as the beginning of a western tradition, it is more fruitful to think of the homeric poems as coming at the end of a long tradition of in-performance improvisation, where poets recut the cloth of what they had inherited to weave new stories. the way into thinking about the oral traditionality @xcite of these poems is through their language, and, in particular, the repeated phrases or epithets that have long been regarded as a characteristic feature of them. phrases such as "swift-footed achilles" -a line that recurs throughout the iliad, for example -are not designed to capture a moment in a specific way but rather "trigger a chain of associations" @xcite in the minds of audiences, who have grown up with these stories and poems of this kind. the more familiar with other (earlier) uses of such phrases, the more an audience can derive meaning from their present application @xcite . since "oral poetry works like a language, only more so" @xcite , there is great potential in leveraging language modelling for better understanding how the homeric poets have been put together. such work might not be able to resolve the so-called homeric question: whether, that is, one person -let's call him homer -composed both (or one of) the iliad and odyssey in the form that have come down to us. yet, it is the contention of this paper that language modelling can lift the curtain on the mechanics of oral competitive poetics, either by drawing attention to the points of connection between the poems or to other epics (such as those of hesiod), or, on the contrary, by revealing moments of rupture from the norm. in this way, we hope to set out some ground rules for identifying, and thinking about, the practice by which individual passages generate meaning by playing on audience expectations and their very familiarity with traditional story patterns, themes, and phraseology. our starting point is the holm resource, developed to assist scholars studying linguistic heterogeneity within the homeric poems at the level of different structural elements (verses, passages and books) @xcite , where related work is also discussed. in this study, we use the cross-score metric to calculate the number of verses per book exhibiting greater linguistic affinity (i.e., reduced surprise) with the opposite poem than to their original source poem. such verses, either individual or in clusters, suggest complexities beyond simple interpolations. they hint at potential contamination between the poems or common origins for specific passages. as a means of generating supplementary data complementing existing material, we train three text classifiers to assess the verses of nine books selected from both poems, five from the iliad and four from the odyssey. ## motivation and method our objective is to broaden the scope of research on the phenomenon of unexpectedness by moving beyond the mere identification of surprising verses or passages within a model trained on the source text. among the verses identified as unexpected in holm, we perform a quantitative analysis specifically on verses/passages that appear to be linguistically more surprising to their immediate surroundings than to other, more remote parts of the homeric poems. in short, we focus on three levels of surroundings that provide increasingly broader contexts for assessing the linguistic surprise of verses or passages: we investigate this level by seeking consecutive or near-consecutive outlier verses. this method lays the groundwork for investigating internal transposition of text within each poem, as well as odyssean elements in the iliad and vice versa. further systematic study of such passages may help not only unveil patterns of interpolation itself, but also to shed light on what is consciously or instinctively perceived as 'iliadic' or 'odyssean', thereby ultimately unlocking insights into the agonistic, compositional basis of either poem. ## zooming in as is appropriate for works with such a lengthy and involved compositional history, the macroscopic book-level analysis ultimately aims at identifying distinctive narrative segments with higher concentration of pcvs, indicating a closer affinity with the other poem than their source poem. using the books that stood out in the statistical analysis of pcvs, we focus on iliad 1, 2, 9, 10 and 24. book 10 is probably the most discussed book in terms of its authenticity; it is still commonly regarded as interpolated (or at least extended parts of it) @xcite . book 2, which heralds 'the great gathering of armies', has also been discussed extensively in the literature (see for instance @xcite ), again due to its atypical content, since it includes extensive lists, not least of which is the famous catalogue of ships. however, it is book 24 that stands out from our book-level analysis of the holm resource: it exhibits the highest number of pcvs (fig. 1 ) as well as the highest rate of locally surprising verses (fig. 4 ). from the odyssey, we selected books 11, 15, 22 and 24, the ones with the highest number of pcvs. book 11 demonstrates in addition the highest number of high local ppl in the poem. together with book 24, they also present a more coherent picture of surprising passages with high concentration of pcvs (groups of verses clustered in close proximity). ## discussion compared to the pcvs, a large number of groups of source-surprising verses (up to four excluding duplicates) can be readily observable in all of the individual books evaluated by the ml classifiers. further merging groups located closely together requires closer examination and carefully selected criteria. it is, however, feasible to discern potential patterns among some of the passages picked out. these include lists (such as the catalogue of ships in iliad 2 and the list of women in odyssey 11), but also a number of similes, as well as narrations referring to the past. from a literary perspective, the books that emerge as related to the 'other' poem reveal close correspondences. these moments of contact could simply be down to the protagonist of either poem and their prominence in the other poem, namely odysseus in iliad 2, 9 and 10, and achilles in odyssey 11 (noting that the wrath of achilles is the headline of the iliad, and the return home of odysseus the subject of the odyssey). but, as well as being insufficient to explain all the cases (particularly in the odyssey), the presence of the protagonist arguably better indicates heightened moments of thematic cross-over between the epics. as well as being prominent in these books of the iliad, odysseus also acts in an 'odyssean' manner, most notably in iliad 10, the book which some critics still doubt or consider as a late 'add on', precisely because of its seemingly uniliadic story of night adventure, ambush and deceit (led, of course, by odysseus) @xcite . in iliad 9 odysseus is prominent as the leader of the embassy to achilles, where his rhetorical skills are on display (and seen through by achilles). in iliad 2, odysseus again takes control of the narrative, after agamemnon's disastrous 'testing' of the troops: it is odysseus to whom athena goes (as she so often does in the odyssey) and who notably holds back the achaeans as they rush to the ships to go home, an event that, the homeric narrator remarks, would have been 'beyond fate' @xcite .. the rivalry between these alternative epic traditions is taken up in odyssey 11, where an ambushed achilles is left behind in the underworld bemoaning his early death and anxious for news of his son, even as odysseus continues on his journey home to reunite with his l @xcite . odyssey 22 is the moment when odysseus's banqueting halls become an iliadic battleground, as odysseus takes on and slaughters all the suitors who have been eating his son out of house and home. odyssey 24 opens with another scene of (un)iliadic heroes in the underworld -achilles and agamemnon praising each other no lessand culminates in another battle, when odysseus, accompanied by both his father and son, takes on and kills the families of the suitors @xcite . it is also striking that the beginning and ending of the iliad is marked out as resonating strongly with the other tradition, as if self-consciously aware of its place in the tradition. analysing individual passages is simultaneously more straightforward and open to speculation, especially in defining their boundaries. nevertheless, a number clearly stand out when considering both pcvs and the ml models classifications. such an example of source-surprising verses is in iliad book 10 (263-279) where the arming of odysseus is described in a distinct section of the book. in the odyssey, the models mark as source-surprising the catalogue of women in book 11 @xcite . this is also a section mentioned in literature as a possible interpolation and further discussed in the same context in @xcite . ## conclusions our two methods for assessing the level of interpoem surprise largely converge in identifying specific books and passages as notably surprising within their respective poems. an initial expert analysis of the flagged passages reveals potential patterns recognized by the models; notably, books 1, 9, 10, and 24 of the iliad and books 11, 15, 22, and 24 of the odyssey contain the highest concentration of such verses. within these books, shorter passages appear to contribute more significantly to these findings. further analysis of shorter verse clusters with positive or almost positive cross score seem promising in revealing both linguistic and thematic criteria associated with either poem. it may also reveal lexical features that weigh more in each poem's language modelling. future research may focus on these aspects, including catalogs, direct speech, gender-related topics and discourse, as well as proper names and content words. additionally, it should aim to examine the homeric poems within their closer historical context and model them alongside other ancient au-thors and genres, such as hesiod and lyric poetry.