[3.24.1] Quare quaedam aquae caleant: A question that numerous thinkers pondered, including Empedocles (see note infra), Aristotle Mete. 359b514, Vitr. 8.2.9-8.3.2, and Pliny Nat. 31.59-61. See Clendenon 2009: 165-171 for more on hot springs in Greece (where most of the heating is geothermal and not volcanic) and Campbell 2012: 338-68 for more on bathing culture, spas, and healing springs in the Roman world. Plutarch mentions that it is common to wonder at hot springs, but not at the more ubiquitous cold springs (Q.N. 29.919AB, see the recent commentary by Meeusen 2016: ad loc.), a topic that continued in the Renaissance (see Park 1999).
quaedam etiam ferveant: Hot springs in volcanic areas are often at or near the boiling point and can cause severe burns or even be deadly. The National Centers for Enrivornment Information issues a map of thermal springs in the U.S. where the temperatures range from “Boiling” to “Warm”.
in tantum ut non possint esse usui, nisi aut in aperto evanuerunt aut mixtura frigidae intepuerunt: Pliny mentions that the spring called Posidian near Baiae is so hot that it is said to cook meat (obsonia quoque percocunt, Nat. 31.5). At Yellowstone, certain hot springs can be well over 200 degrees Farenheit. For other uses of in tantum ut in Seneca, cf. e.g. NQ 4b.11.1, Ben. 2.16.2, 3.32.2, Ep. 14.11. See Ep. 98.1, Cl. 2.5.3 for similar expressions of the predicate dative usui (OLD 11b). Seneca first uses intepescere to mean “to cool down, to make lukewarm” (OLD 2a), cf. Ep. 67.1, 78.23. mixtura is ablative of means, and Seneca earlier wrote how personalities are created by hot and cold elements and “a mixture of cold creates cowards” (frigidi mixtura timidos facit, Dial. 4.19.2).
plures causae redduntur: He will give two and agree with both. Multiple causation was a constituent element of Epicurean science, but whereas that meant to explain phenomena for which it was “sufficient for our happiness that several explanations be discovered” (Asmis 1984: 321), Seneca does so to explain why some hot springs can offer pure water while others will taste of sulphur or nitrum. For Seneca’s discussion of Epicurean multiple causation, cf. NQ 6.20.5.
Empedocles existimat ignibus quos multis locis terra opertos tegit aquam calescere: This is Graham 2010: 94 = DK 31A68. Empedocles was a 5th C. BCE philosopher from Sicily and is associated with Mt. Etna (where he is said to have immolated himself) so one may expect that he would be familiar with its volcanic landscape (cf. Graham 2010: 428). Empedocles also developed the idea of the four elements (fire, air, water, earth) and stressed the importance of mixture “there is no birth of any of all mortal things, neither any end of destructive death, but only mixture (μίξις) and separation of mixed things (μιγέντων) exist” (Graham 2010: 32 [F 11] = DK 31B8), which Seneca may foreshadow with his use of mixtura previously. For more on Empedocles’ belief in four elements, cf. note on 3.9.1 supra. This section the only time that Seneca mentions Empedocles by name in his works, and Setaioli believes that it probably comes from a second-hand source (1988: 56), but Empedoclean thought was clearly well-disseminated at this period (cf. Garani 2007, Campbell 2014, but Farrell 2014 voices some suspicion). Magma chambers are able to heat the water that passes near them, a common enough phenomenon in Sicily and Pliny remarks on the hot springs of Segesta (Nat. 31.61) and springs even at the foot of Etna (Nat. 2.234). Seneca writes of fires in the earth at NQ 2.10.4: adice nunc ignes, non tantum manufactos et certos, sed opertos terris… A recent study highlights the hydrological basis of Etna's eruptions.
si subiecti sunt ei solo per quod aquis transcursus est: Seneca often uses forms of subicere of fire (Herc. F. 507-8: coniugem et totum gregem / consumat unus igne subiecto rogus, Ep. 66.38, and of boiling water, NQ 6.11.1: videmus aquam spumare igne subiecto). transcursus here is the noun “a rapid movement across”, for a similar use, cf. NQ 2.7.1. The movement of water over the hidden fires must be quick or else the water would turn to steam, which, in fact, causes geysers.
[3.24.2] facere solemus dracones et miliaria et complures formas: This appears to be the only time dracones appears in Latin to describe this heating apparatus, TLL 5.2064.42-45. Obviously it is named so because it was coiled around the flame in a snake-like manner to heat the most surface area of water at the same time. Seneca will later discuss miliaria (small boilers that heat swiftly and keep their heat longer because of the size of their pipes) in Democritus’ explanation of heat at NQ 4b.9. For a recent discovery of a milarium with illustrations, cf. Hurard, Leconte, Lefeuvre, and Raymond 2016 and for more on its use in baths, see the comparanda at TLL 8.948.66-84.
in quibus tenui aere fistulas struimus per declive circumdatas: tenui aere is ablative of material (A&G 403) and helps the reader understand how these pipes can be made to coil around the fire in such a “downhill” (per declive, cf. Ovid Met. 2.206) gradient. Seneca will elsewhere employ a “domesticating use of analogy” (Williams 2012: 220) involving pipes to describe rainbows created by water erupting from a burst pipe (NQ 1.3.2, 1.5.6). Roby 2014: 163 focuses on this example “persuasion depends not on emphasizing the exotically high technology of laboratory equipment, but on reinforcing the sense that the reader experiences this phenomenon every day – and he can see it happen right in front of him in the text”. In this case Seneca’s employment of a Roman boiler with specific Roman terminology helps to Romanize the Greek philosophical material – notice how explicit references to Empedocles bookend this technical ecphrasis. For more on technical ecphrases, cf. Roby 2016. If the earth is like a human being, Seneca works to expand the analogy so that human inventions can help to explain terrestrial marvels.
ut saepe eundem ignem ambiens aqua per tantum fluat spatii quantum efficiendo calori sat est: “that often the water flows down around the same fire, just as much as it is necessary to make it hot”.
frigida itaque intrat, effluit calida: The chiastic structure highlights the before (frigida) and after (calida) and the movements into (intrat) and out (effluit) of the apparatus. This answers quaestiones posed at NQ 3.1.2 supra about whether waters are born hot or made that way. For the contrast between hot and cold as intrinsic to the elements, cf. NQ 7.27.4: non vides quam contraria inter se elementa sint? Gravia et levia sunt, fridiga et calida, umida et sicca; tota haec mundi concordia ex discordibus constat.
[3.24.3] idem sub terra Empedocles existimat fieri: The similarity (idem) highlighted by the analogy is stressed by repeating the language that began the investigation (Empedocles existimat).
quem non falli crede Baianis, quibus balnearia sine igne calfiunt: For credere + dat. and acc./infinitive construction (s.v. credere 4a), cf. NQ 7.14.1: quid sit quare credamus illi tantam esse crassitudinem caeli. balnearia is the neuter plural of the adjective used to denote private “baths” as at Dial. 9.9.7: inter balnearia et thermas. Seneca devotes a letter to his experience at Baiae (Ep. 51) and strongly condemns the lax morals of this resort town (a commonplace from Cicero Cael. 15 onward). See Edwards 2018: 186-88 for a reading of Campanian letters (Ep. 49-57). Seneca acknowledge the natural advantages of this area, which Strabo seconds (5.2.9), but, for Seneca, the problem is that the luxury has claimed the town for itself (quia illum sibi celebrandum luxuria desumpsit, Ep. 51.1). For more on the bathing complex at Baiae, see D’Arms 1970: 97-101 for Nero’s use of Baiae and 110-11 for excavations of the baths, and Yegül 1996 for interpretation of the remains. Due to volcanic activity and bradyseism much of Baiae’s remains are underwater now. Propertius mentions Baiae’s “smoking waters” (fumida Baiarum stagna tepentis aquae, 3.18.2) and Statius Sil. 3.5.96 notes “steamy Baiae” (vaporiferas…Baias), its famous baths (1.50.60), and its “safe” volcanism (5.3.170-71). The powerful steam at Baiae can boil cold water (Pliny Nat. 31.5) or be employed in steam rooms (Vitr. 2.6.2, Celsus 2.17.1, D.C. 48.51). For Seneca on baths in general, cf. Ep. 56 and Ep. 86 (with Henderson 2004: 32-33 (Baiae) and 93-170 on Ep. 86, Rimell 2015: 157-98). For poetic associations of Baiae from Catullus to the Anthologia Latina (Kay 2006: 130-31) to Pontano (Dennis 2006), see the special issue of Illinois Classical Studies 40 (2015) with contributions that stress the area “as both a center of literary activity and an imaginative fulcrum” (85).
spiritus in illa fervens loco aestuanti infunditur: spiritus…fervens probably indicates steam, but also drawing upon the conception of the living earth having “breath” (cf. note on NQ 3.pr.15 supra). Although infundere is usually used of liquids, Seneca also employs it of the air at NQ 6.14.3. Lucretius stresses how this area is known for such emissions: hos igitur tellus omnis exaestuat aestus (6.816, of the area around Avernus). Paget 1967a and McKay 1972: 46-51 write about the Great Antrum, which was probably used to conduct heat to the bathing complex and was still “exuding hot sulphurous gas” Paget 1967a: 103 when discovered. I doubt it was a ritual entrance to the underworld, as popularized by Paget 1967b. For use of such vapors in the “small bath” at Baia, cf. Medri, Soricelli and Benini 1999.
hic per tubos lapsus non aliter quam igne subdito parietes et vasa balnei calfacit: It was common for Roman baths to have “hollow, box-shaped tiles that were stacked on top of each other against the wall to form, in effect, tall vertical tubes” running through the walls that were heated by the hypocaust (see Yegül 2010: 86-89). Seneca derides radiant heat as a harmful luxury and unworthy of a wise man at Dial. 1.4.9 and Ep. 90.25. vasa here probably means “pools”. Vitruvius writes of a vasaria a “room containing vessels for heating baths” and it is possible that it should be read here. As Yegül 1996: 142 states of the bathing complex at Baiae: “Other units, particularly the small, domed ones, must have been intended for sweat bathing…[with] natural steam conducted into them through underground galleries and conduits…many of the vaulted and domed rooms have conventional hypocausted floor raised on pilae, but they were heated by natural hot gases rather than furnaces”.
omnis denique frigida transitu mutatur in caldam: Cold water becomes hot by means of traveling over the steam-filled pipes or rooms. This transformation can be paralleled with the elemental transformations earlier (NQ 3.10.3-3.10.4), which likewise stressed forms of transire and mutare.
nec trahit saporem e vaporario, quia clusa praelabitur: For trahere+saporem, cf. Col. 12.52.21. The vaporarium was a room in which steam circulates to heat additional areas (cf. Cic. Q.fr. 3.1.2). At Baiae, many of these chambers were cut out of the natural rock in areas that possessed steam vents. The fact that pipes influenced the taste of water (and knowledge of lead poisoning) is apparent in Vitr. 8.6.10-11, but here pipes or pools of water would not be infused with the taste of sulphur gas, cf. NQ 3.20.1-2 supra for the way tastes of water can be corrupted.
[3.24.4] quidam existimant per loca sulphure plena vel nitro: The other method by which waters may be heated involves the make up of the soil. Kertsch 1980 believes quidam here denotes Posidonius and possibly Theophrastus (contra Steinmetz 1964: 256 who believed it was only Theophrastus). Vitruvius claimed that passing through these locations would affect taste, but not temperature (8.2.8). Seneca associates sulphur and nitrum with bitumen supra NQ 3.20.2. Sulphur, of course, was associated with fire because it is flammable, cf. Ovid Rem. 731: paene extinctum cinerem si sulphure tangas, vivet, Lucr. 6.747, Pliny Nat. 35.177. Pliny Nat. 31.106-22 mentions uses of nitrum (from the Arabic natron), which was probably “a mixture of sodium carbonate, calcium carbonate, and various chlorides” (Jones 1963: 567). Alkaline springs are very common, as Pliny acknowledges (Nat. 31.107: aquae vero nitrosae plurimis in locis reperiuntur) and can be found around the Lago di Vico in Etruria. While nitrum is not as associated with fire in the same way that bitumen and sulphur are, it was often “cut” with lime (see infra), which caused it to crackle in fire (Pliny Nat. 31.114) and it produced a warm sensation in certain medicines (in medicina autem calfacit, Pliny Nat. 31.115).
calorem beneficio materiae per quam fluunt trahere: Seneca will use trahere + calorem at NQ 7.1.6 of comets: quae per igneos tractus labentia inde splendorem trahant caloremque. beneficio + gen. = “thanks to” (OLD 4), see Dial. 5.2.1: quaedam gentes beneficio egestatis non novere luxuriam. For more on materia in the NQ, cf. the note on 3.19.4 supra.
quod ipso odore gustuque testantur: For the conjunction of smell and taste elsewhere in Seneca, cf. Dial. 5.10.3: et odore gustuque quidquid est quod alienat animos repellitur, cf. Dial. 9.4.7 and NQ 3.25.1 infra. testor usually has legal overtones and is only found with the ablative here in Seneca “a fact that they demonstrate by its very odor and taste”.
reddunt enim qualitatem eius qua caluere materiae: reddunt now with aquae as subject. qualitas also can found in Seneca’s description of grafting trees at Ep. 112.2, and the way that the supreme good can take on different forms at Ep. 66.7-8, but only here in the NQ.
quod ne accidere mireris, vivae calci aquam infunde: fervebit.: Once again Seneca moves to the second person to address the reader and limit any sense of surprise. viva calx denotes quicklime, which undergoes a violent exothermic reaction and produces enough heat to boil water. Pliny noted the same reaction (Nat. 33.94: viva calx aqua accenditur). The final fervebit recalls this chapter’s opening line quaedam etiam ferveant and Seneca has worked hard to repeat his language and denude it of wonder (note, in addition, the spiritus…fervens…infunditur of 3.24.3). This final example, taken from everyday experience, would seem to cinch his argument and show how even boiling hot waters can be easily explained.
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