It is puzzling that hortus and any related term appear nowhere in the De rerum natura (henceforth DRN). The word naturally appears in conjunction with terms such as seges, ager, uilla, uinetum, pecudes, arbustum and agellus (for example Cato, Agr. 36.1; Cic. Sen. 54; Varro, Rust. 3.10; Columella, Rust. 4.18.1). So expected are these pairings that Lucretius’ choice to omit hortus in an outpouring of agricultural diction at 5.1361–78 (including agri, agellus, cultum, uinetum, seges, plaga) demands explanation.Footnote ¹ Compounding the dilemma is the fact that the term is missing in a work promulgating the teachings of the Garden, the Epicurean school's long-established nickname (for example Diog. Laert. 10.17; Cic. Nat. D. 1.120).

We might attribute the absence of hortus (κῆπος) to Lucretius’ discomfort with invoking, even incidentally, that nickname. But unless Cicero's mocking employment of the diminutive hortulus somehow scared off Lucretius (for example Leg. 1.39; De or. 3.63), internal and external evidence for this motivation are wanting. Philodemus, Lucretius’ contemporary, seems to have used the moniker without compunction (κῆπος; P.Herc. 164, 1021 col. 14). Metrical considerations for employing hortus and related forms similarly fail to explain the omission. Nor does hort-, when vocalized, prompt any infelicities that the poet might wish to avoid.Footnote ² But things become weirder when we consider that even the homophonic but etymologically unrelated hort- of hortari (‘encourage’) and all related forms—including the compounds dehortari (‘advise against’), adhortari (‘urge on’) and exhortari (‘admonish’)—never appear in the poem. To contextualize their absence in the DRN, we can note their regular occurrence across Cicero's surviving works. Lucretius’ abstention is even more surprising since, as Marković observes, ‘The poem as a whole can be described as an unusually well argued and documented act of moral exhortation.’Footnote ³

My tentative explanation for this dual mystery has two related parts. First, although noticeably absent in contexts where we might expect hortus, the term does surface in the poem and in a way that specifically links it to Epicurus. Lucretius identifies his teacher only once—to stunning rhetorical effect—near the centre of the poem in an argumentative crescendo against the fear of death (3.1042–4):

The argument crests with the following question: if even Epicurus necessarily perished, ‘will you then falter and resent dying?’ (tu uero dubitabis et indignabere obire?, 3.1045). The light/life and astral/solar imagery is immediately patent, but the ear hears additional interpretative valences. Since pronunciation of the x of exortus would largely overpower a subsequent aspirate, we cannot avoid hearing hortus when line 1044 is scanned aloud. ortus and hortus have no etymological relationship, but that would not prevent Lucretius, like Varro and others,Footnote ⁴ from sensing or playing on one here, especially given the organic use of orire in contexts of plant growth (exorta … arbusta) and sunshine (in luminis oras, 1.179–87).Footnote ⁵ Similarly, in other sections about tillage and crop raising, we encounter the phrase ad ortus, ‘for the purpose of plant growth’, and it is not far fetched to think that an audience might hear ad hort and think ‘for the purpose of a garden’, which altogether coheres with those agricultural contexts (1.206–12; 5.206–12). At any rate, it would be a strange coincidence if, in the only location to name Epicurus and, as Snyder demonstrates, to contain layers of wordplay on his name (Epicurus … decurso), we also encounter a phonically detectible hortus.Footnote ⁶ Perhaps we should understand the image to be Epicurus as both the life-giving sun and an embodiment of the garden it nurtures.

Second, if we hear hortus at this singular mention of Epicurus, we might also hear the exhort- of exhortari, a word we reasonably expect to find in a protreptic poem. What is more, the frequentative hortari was likely constructed from hortus, the reconstructed perfect passive participle of horior, an outmoded verb used by Ennius (Ann. 432) and certainly known to Lucretius.Footnote ⁷ When these verses are recited aloud, our ears sense that Epicurus, like the sun, rises above all and delivers to them the hard exhortation against fearing death since, like sunrise and sunset, it cannot be divorced from nature's perpetual revolution.Footnote ⁸ Perhaps it is also a simultaneous encouragement toward joining the Garden, a heavenly way of life (aetherius) that Lucretius trusts to be attainable here and now (cf. 3.322). A final oddity that feels more than coincidental is the fact that the exact form exortus—masculine, singular, nominative like the noun hortus or the participle exhortus/exhortatus agreeing with Epicurus—appears only here in the poem.Footnote ⁹ In contrast, the participle ortus occurs elsewhere (for example 4.432; 6.1141) and, with some metrical adjustment, the simplex would have served adequately in line 3.1044. It seems that Lucretius purposefully reserves this particular gender, number and case of the compound for this unique appearance.

We are still left with the mystery of Lucretius’ total avoidance of all forms of horiri/hortari. If we are right to hear exhortus/exhortatus at 3.1044, linked as it is to Epicurus, we might conclude that Lucretius presents the teacher as the only valid source of moral exhortation. This would conform with the poet's frequently expressed reverence for Epicurus (for example 3.9–15; 5.1–13), whose footsteps he follows and with whom he cannot vie (3.1–8). On the other hand, when Lucretius depicts his own role, he uses the language of explanation (for instance ratio, 1.28–30), teaching (for example docere, 3.31), expanding (for instance pandere, 1.55), clarifying (for example claranda, 3.36), expounding (for instance rationem exponere, 1.946; 4.21), illuminating minds (for example praepandere lumina menti, 1.144) and, of course, honeyed inducement (1.936–50; 4.11–25). There is only one Epicurus ex(h)ortus, as 3.1042–4 seems to emphasize.