From this and the following lines we may infer that Aeneas answers Deiphobus' question, and that the conversation proceeds. The lines are imitated, though with additional elaboration, from Od. 11. 81, 465 foll.: Virg. also thought of Apoll. R. 2. 448 foll. ‘Vice sermonum’ translates ἐπέεσσιν ἀμειβομένω. “Vice sermonis” occurs Ov. 4 Trist. 4. 79, “vicibus loquendi” Id. 2 Ex Pont. 10. 35, cited by Forc. The abl. here is one of circumstance. ‘Roseis Aurora quadrigis:’ comp. 7. 26, where the Dawn goddess appears “in roseis bigis,” a number agreeing with the Homeric accunt Od. 23. 246. It matters little whether we suppose the car or the horses to be designated by the epithet ‘rosy,’ nor yet whether the abl. be taken as instrumental with ‘traiecerat’ or as descriptive with ‘Aurora.’ Considerable difficulty has been made about the time intended by the poet: but Wagn. rightly follows Cerda, who supposes that Aeneas spends a night, a day, and perhaps a second night in or about the infernal regions, the first night being devoted to the preliminary sacrifices, the whole of the succeeding time to the journey through the shades. They started at daybreak, vv. 255 foll.: they have been exploring till past noon, and now the Sibyl warns Aeneas, in language sufficiently natural, that night is hastening on, ‘nox ruit.’ The amplification is perhaps a little unseasonable, as we searcely need to be reminded pointedly of what is going on in the upper world, though of course all notation of time must be made by a reference to daylight.
 Axis of the heaven G. 2. 271. ‘Medium axem’ like “medium sol igneus orbem Hauserat” G. 4. 426. ‘Cursu’ instrumental, if ‘quadrigis’ be descriptive; otherwise we must take it ‘in’ or ‘during her course,’ as in v. 338 above.
 Perhaps from Od. 16. 220 (repeated 21. 226), καί νύ κ᾽ ὀδυρομένοισιν ἔδυ φάος ἠελίοιο. This mode of saying that something would have happened if it had not been prevented by something else, is common in Hom. to a degree which would appear grotesque in a less simple writer. ‘Datum,’ by the gods or by the Sibyl: see on v. 477. What the time assigned was we can only infer: but we may reasonably suppose that a visit to the shades would have its limits. ‘Per talia:’ Virg. has chosen to say ‘they would have drawn out their time through such conversation as this’ instead of ‘they would have drawn out such conversation as this through their time.’ So “nos flendo ducimus horas” v. 539. For ‘traherent’ see on 1. 748. Here and in v. 539 the notion seems to be that they were spending a long time in talking or weeping; though from another point of view it might have been said that they were making the time go fast. Comp. 5. 766, “Conplexi inter se noctemque diemque morantur.”
 “Comes admoneat” v. 292 above. For ‘Sibylla’ after ‘comes’ see on 3. 162. Perhaps however it is better to say here that ‘comes’ qualifies ‘admonuit’ on the principle illustrated on E. 8. 1, 18, ‘admonished him as a companion,’ so that it really = “comitem admonuit.” Virg. is fond of adverting to the brevity of the Sibyl's speeches: see vv. 321, 398.
 Hitherto they had passed along a single road, the district being inhabited by those who were neither in happiness nor in pain; now the ways diverge to Elysium or to Tartarus. Plato, Gorgias, p. 524 A, makes the judgment take place ἐν τῇ τριόδῳ, ἐξ ἧς φέρετον τὼ ὁδώ, ἡ μὲν εἰς μακάρων νήσους, ἡ δ᾽ εἰς Τάρταρον. ‘Ambas’ for “duas,” a use noted by Serv. and Donatus, and also by Forc., but not illustrated by other instances. We might say ‘where the way divides into its two parts;’ but we should still not give the force of the word, as ‘both’ not merely supposes the parts as already known, but expressly negatives the notion, which here no one would dream of entertaining, that one part only is in question.
 It is slightly neater to remove the comma usually put after ‘dextera’ with Jahn, as we must otherwise suppose an anacoluthon. ‘Ditis magni sub moenia:’ see vv. 630 foll. We may comp. the lines on the Pythagorean Y, Pers. 3. 56, “et tibi quae Samios diduxit litera ramos Surgentem dextro monstravit limite callem.”
 The road is said to punish the bad and send them to Tartarus, a kind of hendiadys, expressing what would be expressed in less artificial language by saying that it conducts them to Tartarus where they are punished. We have already had an instance of Virg.'s variety in the use of ‘exercere’ on G. 3. 152; here and in v. 739 there is a somewhat analogous variety, ‘exercet poenas’ and ‘exercentur poenis.’ Tac. A. 1. 44, comp. by Forb., has “iudicium et poenas de singulis exercuit.” The way is said ‘mittere,’ as elsewhere “ducere” or “ferre.” ‘Impia Tartara,’ the epithet properly belonging to the occupants of the place transferred to the place itself, not unlike “lugentes campi” v. 441.
 Serv. gives a choice of interpretations of ‘explebo numerum,’ one impossible, ‘explebo’ = “minuam,” which he supports by Enn. A. 9. fr. 5, “Navibus explebant sese, terrasque replebant,” the others more conformable to Latinity, ‘I will fill up the number of the shades by rejoining them,’ and ‘I will fill up my allotted time in the shades.’ Macrob. Som. Scip. 1. 13 has a mystical explanation of the words from Plotinus' doctrine of numbers, which the curious in such things may consult. On the whole Heyne seems right in preferring Serv.'s second interpretation. Forb. comp. Sen. Hipp. 1153, “Constat inferno numerus tyranno,” supposing Virg. to intimate that Pluto would naturally be jealous of the prolonged absence of one of his subjects. Comp. the use of ‘numerus’ E. 6. 85. There are two other passages in Seneca's Tragedies which may illustrate this use of ‘explere,’ Herc. Oet. 949, “Vacat una Danais: has ego explebo vices,” and Herc. F. 502, “Deest una numero Danais: explebo nefas.” But the interpretation can hardly be said to have been as yet placed beyond doubt. Mr. Long suggests that ‘numerum’ may mean ‘my place,’ a sense illustrated on G. 4. 227.
 “Tantum effatus, et infesta subit obvius hasta” 10. 877. ‘In verbo vestigia torsit’ is like “media in voce resistit” 4. 76, ‘in verbo’ meaning ‘even while he was speaking,’ to show Deiphobus' ready compliance. For ‘torsit’ Med., Rom., and one or two others give ‘pressit,’ which, if genuine, must be understood to mean that Deiphobus, having followed Aeneas and the Sibyl previously, at length stopped, and left them to pursue their journey. But ‘vestigia pressit’ has already occurred twice in this book, vv. 197, 331, and so would naturally suggest itself to a transcriber, while it is more likely that Deiphobus should be represented as moving away, which he would have to do (comp. v. 545), than as simply stopping. “Ad sonitum vocis vestigia torsit” 3. 669.
[548-561] ‘Aeneas sees a huge fortress on the left, surrounded by a fiery river, and echoing with sounds of torture, and inquires the meaning of it.’