For helpful comments and questions, my thanks to audience members at a Cambridge seminar on first-century BC philosophy in 2006–7, and at the April 2019 Lucretius conference in Paris; also to Maeve Lentricchia and Voula Tsouna for further discussion, and to Barnaby Taylor for kindly letting me read his energising draft chapter on Lucretian metaphor (including epibolē), due to appear in Barnaby Taylor, Lucretius and the Language of Nature (Oxford 2020).

[Do not suppose that,] whereas your eyesight can reach many stades, god’s eye cannot see everything at once; nor that, whereas your mind can care both about things here and about things in Egypt and Sicily, god’s wisdom is not sufficient for him to concern himself with all things at one and the same time.

3In the proem to his first book, Lucretius praises the similarly synoptic vision of a great Greek predecessor, reverentially left unnamed but instantly recognisable as Epicurus:

• 4 humana ante oculos foede cum vita iaceret / in terris oppressa gravi sub religione, / quae caput a (...)

At a time when before his very eyes human life was squalidly sprawled on the ground, oppressed by the weight of the religion that reared its head from the heavenly regions, louring over mortals and terrible to behold, it was a Greek man who first had the courage to raise those mortal eyes against it, and was the first to stand up against it. He was held back neither by the tales of the gods nor by thunderbolts nor by the heaven with its threatening roar, but these all the more stirred up the intense valour of his mind, making him desire to break open the tight-shut bars of nature’s gates. As a result his mind’s vibrant energy fought its way through and issued forth, far beyond the flaming walls of the world, and he roamed with his intellect and mind through the measureless universe. From there he returns victorious, to report to us what is possible, what impossible, and moreover how each thing’s power is delimited, and its deep-set boundary stone. As a result, religion is in its own turn trampled underfoot, while his victory raises us heaven high.4

4The divine character of Epicurus’ achievement is not yet made explicit: that apotheosis is being saved for the proem to book 5, a high point of the poem towards which Lucretius is already working. Instead the great man is at this stage compared to a victorious general. He was the first to fight back against the crushing effects of false religious belief, and he did so by a progression from ocular to mental vision. First, using his own eyes, he could see human life to be everywhere oppressed by religion. He then dared to raise those same eyes to the heaven, from which the menaces of religion were staring down, and to return their stare. This in turn gave him the courage, now by his sheer power of mind, to smash open nature’s gates and issue forth into the measureless universe beyond our own world’s boundary or ‘flaming walls,’ the fiery heaven. Thanks to this extraordinary projection of thought he was enabled to traverse the entire infinity of space, returning in triumph to teach us the limits of the possible and the impossible. In his victory, religion is the vanquished foe, we ourselves the winners.

5There has been much valuable modern analysis of this passage, but from an Epicurean point of view there is no better commentary on it than the following words, spoken by Cicero’s Epicurean Velleius (ND 1.53–56):

• 5 [53] . . . docuit enim nos idem, qui cetera, natura effectum esse mundum, nihil opus fuisse fabrica (...)

[53] . . . For the same man who taught us everything else taught us also that the world was made by nature without the need for craftsmanship, and that this thing which you call impossible without divine creativity is in fact so easy that nature will make, is making and has made infinitely many worlds. Just because you [Stoics] do not see how nature can do this without a mind, unable to develop your plot’s dénouement you copy the tragic poets and resort to a god. [54] You would not be demanding this god’s handiwork if you saw the measureless magnitude of space, endless in all directions, by projecting and focusing itself (se iniciens . . . et intendens) into which the mind travels far and wide, seeing as a result no boundary of its extremities at which it could call a halt. In this measureless stretch of widths, lengths and heights there flies an infinite mass of countless atoms, which despite the presence of void between them stick together and by taking hold of each other form a continuous whole. And from these are made those shapes and formations of things which you [Stoics] think are impossible without bellows and anvil. With this thought you have placed as a yoke upon our necks a permanent overlord, for us to fear day and night . . . [56] Released from these terrors by Epicurus, and delivered into freedom, we do not fear those whom we understand neither to bring trouble upon themselves nor to try and make trouble for others, and with holy reverence we worship their supremely fine nature.5

6Velleius thus brings out what we can achieve for ourselves if we follow Epicurus on his odyssey of the mind. The key to eliminating oppressive creator gods from our world-view is to appreciate the inevitability that mere atomic accident, operating as it must do on an infinite scale, will somewhere at some time produce worlds like our own, without the need for divine craftsmanship. That in its turn requires us to see, by mental projection, what the infinity of the universe really means, just as, according to Lucretius’s intellectual travelogue, Epicurus has already done.

7The sequence of thought-experiments, arguments and mental exercises by which this vision can be achieved is exemplified at length by Lucretius towards the end of his first book (1.951–1051). For example, we are invited to imagine going to some hypothetical boundary of the universe and throwing a spear past it (1.968–83).

• 7 quaerit enim rationem animus, cum summa loci sit / infinita foris haec extra moenia mundi, / quid s (...)

For given the infinite amount of space beyond these walls of our world, the mind demands an account of what further things lie there for the intellect to aim to reach with its gaze, and to which the mind’s projection [animi iactus] can free itself and fly.7

9Lucretius here uses animi iactus, which I have translated ‘the mind’s projection,’ although an even more literal rendition would have been ‘the throwing of the mind.’ Later he uses a slight variant, animi iniectus. Cicero in the passage quoted earlier speaks of the mind se iniciens . . . et intendens, ‘projecting and focusing itself.’ All of these Latinisations capture the –bol– component of the Greek epibolē, from ballein, to ‘throw.’ Despite the similarity between the two Latin authors, the fact that Cicero offers both iniciens and intendens as translations confirms that he is not simply echoing Lucretius’ Latin, but is seeking to optimize his own rendition of the Greek term epibolē, whose nuances both his Latin words help to capture.

10It is clear that in Epicurean thought this technique of intellectual projection applies especially to the appreciation of temporal and spatial infinity. Take temporal infinity first. Remarkably, the mental operation of grasping it is traced back all the way to primitive mankind, for our distant ancestors’ conception of imperishable gods was already enough to show that they had indulged in some such conceptualisation. Consider first Lucretius’ historical reconstruction of how primitive humans first came to think of the gods as imperishable (5.1169–82):

• 8 quippe etenim iam tum divom mortalia saecla / egregias animo facies vigilante videbant / et magis i (...)

For already in those days the races of mortal men used to see with waking mind, and even more so in their sleep, figures of gods, of marvelous appearance and prodigious size. They attributed sensation to them, because they seemed [or ‘were seen’] to move their limbs, and to give utterance with voices of a dignity to match their splendid appearance and great strength. They endowed them with everlasting life, because their appearance was in perpetual supply and the form remained unchanged, and more generally because they supposed that beings with such strength could not easily be overcome by any force. And hence they supposed them to be supremely blessed, because none of them seemed oppressed by fear of death, and also because in their dreams they saw them perform many marvelous acts with no trouble to themselves.8

11In close parallel to this, Sextus Empiricus provides a more technical analysis of the same process as described by Lucretius, or at any rate of the central part of it, reporting the Epicurean theory as follows:

• 9 SE, M 9.46: πολυχρόνιόν τινα φαντασιωθέντες ἄνθρωπον οἱ παλαιοὶ ἐπηύξησαν τὸν χρόνον εἰς ἄπειρον, π (...)

After forming the impression of a long-lived human being, the ancients extended the time to infinite length, joining past and future time to the present, and then, having arrived at the conception of something eternal, said that god is eternal too.9

12The important point of methodology is that the process of projection must start from an ordinary act of imagination, roughly as follows:
– Imagine a very long human lifetime, extending into both past and future.
– Eliminate the birth and infancy of the imagined person, so that their past life is seen as having had no beginning.
– Eliminate the future death of the imagined person, so that their future life is seen as having no end.
– You are now imagining an eternal being, in other words, a god.

13Why did this psychological process ever start? Even the first step, that of imagining a very long human lifetime, was hardly going to happen by accident. Consider the mechanics of imagination in general. As we learn from Lucretius 4.722–822, the mind is at every moment being bombarded with ultra-fine images (simulacra) of all kinds, and each momentary act of imagination requires its concentrating so as to receive the desired kind of image, while ignoring or discarding countless others. So the first step towards conceiving a divine being will probably have been to picture a mature and healthy adult, by drawing into the mind one of the innumerable available images that really did emanate from one or another such person. To add the notion of a long lifetime our ancestors will have had to focus on a series of selected images showing this same person strong, resilient and more or less unchanged in a wide variety of activities and circumstances. By now they had arrived at the conception of a truly durable individual. They then, finally, eliminated the temporal limits altogether. And now they had the conception of an infinitely extended lifetime—one of the essential characteristics of a god.

14As Lucretius explains, when in our dreams people seem to move and act, as these divine figures did, we are not directly seeing them in motion, but are building up a cinematographic effect from the series of momentary images. We are in effect the choreographers of our own dreams (4.800–806, cf. 768–76):

• 10 [800] hoc ubi prima perit alioque est altera nata / inde statu, prior hic gestum mutasse videtur. / (...)

When the first image perishes, followed by the birth of another in a different position, the former person seems to have changed his pose . . . The mind itself moreover prepares for, and hopes to see, the sequel to each thing: which is why it comes about . . . Then we add large opinions derived from slender evidence, and lead ourselves into being tricked by an illusion.10

15It follows that the epiphanies of gods experienced by our ancestors, especially in their dreams, were not any kind of telepathic contact with extra-cosmic living beings, but products of the dreamers’ imagination, converted into fully immortal beings by the further process elsewhere called mental projection.

19I have so far spoken of how conceiving god includes developing the concept of an infinite lifespan. It also includes developing the concept of the second essential characteristic of the divine: supreme blessedness. At 5.1179–82 (quoted above) our ancestors, having conceived these imperishable beings, ‘supposed them to be supremely blessed, because none of them seemed oppressed by fear of death, and also because in their dreams they saw them perform many marvelous acts with no trouble to themselves.’ This arrival at the conception of extreme blessedness is again explicated more technically by Sextus (M 9.45):

• 15 ἄνθρωπον εὐδαίμονα νοήσαντες καὶ μακάριον καὶ συμπεπληρωμένον πᾶσι τοῖς ἀγαθοῖς, εἶτα ταῦτα ἐπιτείν (...)

Having conceived of a human being who is happy, blessed and endowed with his full complement of all goods, we [sic] went on to intensify these characteristics, and conceived one who is at the very summit of them as being a god.15

20No doubt such ‘intensification’ of familiar human blessedness is another case of mental projection. This time, however, there is no question of expansion to an infinity of goods. Admittedly primitive humans did not understand—what would be discovered only in a later age by Epicurus (Lucretius 6.1–42)—that there is a strict limit to the goods that constitute a happy life, so we might expect them to have mistakenly conceived the gods as enjoying an unlimited number of self-indulgences and luxuries. But Lucretius is clear that our ancestors did not make this mistake, and that instead they correctly associated divine blessedness with sublime lack of fear (cf. 1.44–49 = 6.2.646–51). We must therefore suppose that they were drawing not on their mistaken opinions about how to be happy but on their correct innate moral conceptions. If so, the mental intensification that leads to the idea of divine blessedness is likely to consist, not in the quantitative extension of goods, but in the total elimination of even the most minor irritations from the gods’ lives. This will in fact receive strong confirmation later on, in Lucretius’ Homeric picture of the gods’ trouble-free lives (3.18–24).

21The basic conceptualisation of divine imperishability and happiness, attained by all human beings, has served to introduce Epicurean mental projection, but clearly falls far short of the level of understanding that a philosopher can aspire to achieve thanks to the same kind of cognitive leap.

22In an aphorism preserved in the ‘Vatican’ collection of Epicurean sayings, Epicurus’ leading associate Metrodorus writes as follows to a pupil or colleague named Menecles (SV 10):

• 16 μέμνησο ὅτι θνητὸς ὢν τῇ φύσει καὶ λαβὼν χρόνον ὡρισμένον ἀνέβης τοῖς περὶ φύσεως διαλογισμοῖς ἐπὶ (...)

Remember that you, by nature a mortal in receipt of a finite time, have by your discourses about nature ascended to infinity and eternity, and have seen ‘what is, what will be, and what has been.’16

23Nature has allotted Menecles a finite time, yet it is by his inquiries into that very same nature that Menecles has transcended his allotted finitude, to the extent of even challenging his own mortality. The intellectual achievement this time is not simply that of conceiving an eternal being, but that of intellectually mastering the nature of eternity, in a way which has enabled to Menecles himself to aspire to godlikeness.

25It seems that the kind of mental breakthrough celebrated in these passages comes in two stages. In the first stage, some concept that lies beyond direct experience is grasped by such devices as the removal of boundaries. You conceive the infinity of the universe by getting rid, first, of visual obstacles like the sky, later of boundaries as such. You conceive divine eternity by removing temporal limits: first the boundaries of a natural life, and eventually all temporal limits.

26The second stage is that of the intellectual eyewitness, in which you voyage in thought through the new territory you have now opened up. It was this that made Menecles godlike. It is the pioneering act for which we have seen Epicurus praised by Lucretius in his opening proem, and which Cicero’s Velleius says Epicurus has inspired in him and others. And Epicurus’ performance of it was so widely advertised that Cicero himself, speaking as a critic of Epicurean ethics in On ends 2.102, is able to exploit it when mocking the Epicureans about the provisions of Epicurus’ will:

• 18 sed ut sit, etiamne post mortem coletur? idque testamento cavebit is, qui nobis quasi oraculum edid (...)

But setting that aside, is Epicurus’ cult going to be practised even after his death? And will that practice be provided for in the will of someone who announced in the manner of an oracle that nothing after death matters to us. That doesn’t sound like the man who roamed in thought through innumerable worlds and through infinite tracts of space with neither boundary nor limit.18

27For later generations of Epicureans, in short, Epicurus is himself the great exemplar of the conceptual quantum-leap, the act of mental self-projection which results in a transformed vision of the universe.

29Although as it happens we do not find any explicit examples of a phantastikē epibolē tēs dianoias in Epicurus’ fragments and testimonia, I suggest that we can identify one in Lucretius. I am referring to his brilliant demonstration that atoms lack colour (2.730–841). This requires the characteristic Epicurean strategy of eliminating any apparent counter-evidence to the thesis, and it is for that end that Lucretius writes (2.739–47):

• 20 in quae corpora si nullus tibi forte videtur / posse animi iniectus fieri, procul avius erras. / na (...)

If perhaps you think that no projection of the mind (animi iniectus) onto such bodies [i.e. colourless atoms] is possible, you are way off track. For given that people blind from birth, who have never seen the light of the sun, have nevertheless since infancy recognised bodies by touch, with no colour accompanying them, you may be sure that bodies unadorned by any hue can also be conceived by our mind. Moreover, whatever we touch in blind darkness, we ourselves perceive it as not steeped in any colour.20

31This bit of methodology is however quite different from the celebrations of mental projection that we have previously witnessed, celebrations which seem to be part of the school’s attempt to capture the nature of its founder’s pioneering intellectual achievement and benefaction. It may be no accident, then, that the address to Menecles, the one passage on this theme that was selected for the Vatican collection of Epicurean sayings, came not from Epicurus’ own pen but from that of Metrodorus. Another sign of Metrodorus’ likely role is his remark quoted by Plutarch (Col. 1117Β) recommending that we exchange ‘life on the ground’ (ὁ χαμαὶ βίος) for Epicurus’ ‘divine mysteries’ (θεόφαντα ὄργια), quite possibly an ancestor of Lucretius’ talk in his first proem (1.62–63) of how human life lay on the ground until Epicurus elevated it with his new approach to religion. Although Metrodorus predeceased Epicurus, he was regarded by later Epicureans an authority, and it may even have been he who first brought into Epicurean discourse the idea of a transformative mental leap.

32So much for the idea. However, the actual term phantastikē epibolē tēs dianoias does not appear in the citation from Metrodorus, and I have suggested that Epicurus himself sometimes used it in a less elevated way, as a regular test of conceivability. The suspicion may therefore arise that it was not until after Epicurus’ death that the term came to be associated specifically with quantum leaps of the intellect. It is with that possibility in mind that we should consider the following report by Diogenes Laertius (10.31):

• 22 ἐν τοίνυν τῷ Κανόνι λέγων ἐστὶν ὁ Ἐπίκουρος κριτήρια τῆς ἀληθείας εἶναι τὰς αἰσθήσεις καὶ προλήψεις (...)

In the Canon, Epicurus is found saying that sense-perceptions, preconceptions and feelings are the criteria of truth. The Epicureans add phantastikai epibolai tēs dianoias.22

33So it was not Epicurus, but the Epicureans, who elevated the phantastikē epibolē tēs dianoias to the status of a full criterion of truth. A reasonable guess at how this came about is that, having identified and canonised a transformative stage in Epicurus’ own intellectual enlightenment, his successors sought a term for it within the confines of Epicurean canonic, and decided, for better or worse, that phantastikē epibolē tēs dianoias was that term. If I am right that this involved refocusing Epicurus’ original usage of the expression, that change almost certainly occurred after his lifetime.

34Where Epicurus had led, others could follow, including first-century Romans like Velleius and Lucretius. Velleius’ words quoted earlier are one good specimen. Another is Lucretius 3.14–30, a direct address to Epicurus:

• 23 Reading coortam, 3.15.
• 24 nam simul ac ratio tua coepit vociferari / naturam rerum divina mente coorta / diffugiunt animi ter (...)

For as soon as your reasoning begins to articulate the nature of things, sprung from23 a divine intellect, the mind’s terrors turn and run, the walls of the world part, and I see events throughout the entire void. The divine being of the gods appears, and their tranquil abodes, which are never shaken by the winds nor showered upon by the clouds nor assaulted by falls of white snow frozen hard by the sharp frost, but instead are covered by cloudless aether, laughing with its wide-spread light; nature, moreover, supplies their every need, and nothing at any time disturbs their peace of mind. By contrast, nowhere to be seen is the realm of Acheron, although there is no earth in the way to stop everything that happens throughout the void beneath us from being on display. Because of this I am thereupon seized by a kind of divine pleasure and awe, because by your powers nature thus lies open and revealed in every direction.24

35Following a familiar pattern, this passage opens and closes by invoking the inspiration that Epicurus has provided: when Lucretius reads or hears Epicurus’ golden words of divine wisdom, the walls of the world part (moenia mundi / discedunt, 16–17), and he can see for himself, spread out above him, a universe free from interfering gods, as is guaranteed by the accompanying Homeric image of the gods’ perfect tranquillity, free from the slightest irritation; and below him (with the obstructing earth removed) the matching absence of a grim afterlife in hell. Once again, this is cast in terms of eliminating obstacles: the liberated panoptic vision that Epicurus has taught us is one from which the oppressive items have been removed.

37This in turn encourages me to modify my contentions about Lucretius’ isolation from Epicurean movement of his own day. At least one of his ways of canonising Epicurus’ achievement, and of representing our own capacity to emulate it, relies on a school tradition not fully traceable back to Epicurus’ own writings. Moreover, this way of celebrating Epicurus’ superhuman achievement is closely intertwined with a second development also likely to postdate Epicurus’ own lifetime: the founder’s elevation to the status of a god, prominent in Lucretius and well attested elsewhere in the school’s tradition.

38I continue to believe that Lucretius drew his detailed understanding of Epicureanism directly from the revered books On nature bequeathed by the school’s founder, seeing no need to consult lesser Epicurean works written in the two centuries since the founder’s death, and confining his own original contributions to the proems of his six books. Nevertheless, it needs emphasising that the content of his proems is not entirely original and independent. This is not only evident from the obvious fact that it is in the proems, more than anywhere else, that he displays his deep understanding of Epicurean ethics. It is also made clear by the way that in them he shows himself well aware of the school’s consensus about its founder. Epicurus’ pioneering acts of intellectual projection had elevated both him and his philosophical achievement to superhuman status. And Lucretius joins his fellow-Epicureans in celebrating that fact.