Lucretius argues that thunder and lightning have natural causes, for if they are produced by the gods –

The passage is seemingly sound and appears not to have attracted critical attention.Footnote ¹ I propose to argue that fulguris is a corruption, but I admit from the outset that the case against the transmitted reading may, per se, be inconclusive.

To begin with, what exactly does halent mean? Bailey glosses it with ‘reek of’, comparing 6.221 notaeque [sc. fulminis] grauis halantes sulpuris auras (a passage to which we shall return), but there halantes rather means ‘exhaling, emitting’.Footnote ² As OLD s.v. halo makes clear, this is the normal sense of halare with the accusative, whereas the meaning ‘to smell of’ is expressed by halare with the ablative. It seems clear that flammas … halent must mean ‘exhale flames’, as can additionally be confirmed by Enn. trag. 169 Jocelyn quadrupedantes flammam halitantes (of the Sun's fire-breathing horses) or Ov. Met. 15.343 spiramenta locis flammam exhalantia multis (of volcanoes as the Earth's breathing holes), as well as by Virgil's imitation of the Lucretian passage, Aen. 1.44 illum exspirantem transfixo pectore flammas (of Locrian Ajax, struck by Athena's thunderbolt).Footnote ³ Apart from the linguistic considerations, this construal also seems superior in terms of content: seeing someone set aflame by a lightning bolt is much more of a documen than deducing that the person was killed by lightning from the smell of the corpse. The obvious problem is that flammas … fulguris is what a person struck by lightning receives rather than emits, though it can perhaps be got around by taking the phrase to mean something like ‘flames produced by lightning’ or ‘flames of the nature of lightning’.Footnote ⁴ This no doubt was the reasoning behind Rouse's translation: ‘breathe out sulphurous flames’.Footnote ⁵

This I suggest is indeed the sense we need, but it should be obtained not by forcing the transmitted text but by substituting sulpuris for fulguris. Although the shortcomings of fulguris may not be unsurmountable, the advantages of sulpuris seem overwhelming. First of all, it must be noted that the corruption is extremely easy in minuscule script (ſulp- → fulg-) and would further be facilitated by contextual pressure.Footnote ⁶ More to the point, writing sulpuris will produce unambiguous Latin, while also harmonizing the two Lucretian passages describing the effect of lightning: the one speaking about places struck by lightning ‘exhaling sulphurous fumes’, the other about people struck by lightning ‘exhaling sulphurous flames’.Footnote ⁷ In and of itself, this harmonization may not be a strong argument for making the change, but it opens up attractive interpretative possibilities.

One might think that the idea of lightning smelling of sulphur was a commonplace in antiquity, but in fact before Lucretius it is only explicitly attested in Homer.Footnote ⁸ The Odyssey features two identical contexts referring to a ship being struck by a thunderbolt, which as a result ἐν δὲ θεείου πλῆτο (12.417 = 14.307); these appear irrelevant for our present concerns. The other two passages, from the Iliad, have greater potential. One belongs to a simile comparing Hector felled by Ajax to an oak struck by a thunderbolt, which produces a strong smell of sulphur (14.415–16 δεινὴ δὲ θεείου γίγνεται ὀδμὴ | ἐξ αὐτῆς). Given the lack of other pre-Lucretian references to the phenomenon, it is difficult not to connect 6.221 notaeque grauis halantes sulpuris auras to this Homeric passage (grauis ~ δεινή, sulpuris ~ θεείου, auras ~ ὀδμή).Footnote ⁹ Lucretius is there arguing that the sulphurous smell which lightning leaves betrays its fiery nature, and it must have pleased him to be able to derive this physical argument from Homer. The fourth, and last, Homeric passage associating lightning with sulphur is potentially the richest intertext. In Iliad 8 Diomedes and Nestor are about to attack Hector, but are stopped by a thunderbolt striking right in front of them and producing an explosion of sulphurous flames (8.135 δεινὴ δὲ φλὸξ ὦρτο θεείου καιομένοιο); Nestor interprets this as a warning from Zeus (which in fact it is), and the two heroes halt their attack. First of all, if we accept my proposal to read sulpuris at 6.391, here we obtain another exact point of contact between Lucretius and Homer: not only on the lexical level (flammas … sulpuris ~ φλὸξ … θεείου), but also in that the reference is in both cases not to the flame of a lightning bolt as such but to that produced by its strike. While this alone makes sulpuris an attractive correction (we thus have two interrelated Lucretian passages modelled on two interrelated Homeric passages), the context in Iliad 8 also proves a fitting target of polemic allusion. On the one hand, Diomedes and Nestor are exactly the kind of superstitious cowards Lucretius is admonishing his readers not to be. On the other, the fact that the thunderbolt actually misses Diomedes—who, we may remember, wounded Aphrodite and Ares on the previous day—cannot but prove that it was not sent by Zeus: with characteristic irony, Lucretius thus obtains an argument against Homer from Homer himself.Footnote ¹⁰ Virgil, in turn, may be seen to be disputing him when he refers at Aen. 1.44 to Locrian Ajax as being struck by Athena's thunderbolt, in a clear imitation of the Lucretian passage (cf. above).Footnote ¹¹

Textual critics usually ask, before accepting a conjecture, whether we can be certain that the transmitted reading is corrupt; it may be more honest, especially in the case of texts whose tradition is demonstrably unreliable, to ask, before accepting a transmitted reading, whether we can be certain that it is intact. In the case of Lucr. 6.391 fulguris, I admit that the answer to the former question may not be positive; at the same time, especially if we consider the alternative sulpuris, I cannot see how the answer to the latter question can be positive either.