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Published online by Cambridge University Press: 11 August 2020
Modern readers view ancient theories of blood flow through the lens of circulation. Since the nineteenth century, scholarly work on the ancient understanding of the vascular system has run the gamut from attempting to prove that an ancient author had in fact, to some extent or another, pre-empted Harvey's discovery of the circulation of the blood or towards attempting, often with some empathetic embarrassment, to explain the failure on the part of an ancient author to notice something that seems so obvious to the modern eye. Thus C.R.S. Harris's 1973 book The Heart and Vascular System in Ancient Greek Medicine, which remains the standard on the topic, opens with a sentence in which he marvels at how the otherwise admirable ancient Greek physicians could have ‘failed entirely to arrive at any conception of the circulation of the blood’. This modern vantage point has had an unfortunate effect. In the case of Aristotle in particular, understanding of his cardiovascular system has been diminished by a tendency to define it in contradistinction to our own modern understanding of circulation. By deliberately uncoupling from the framework of modern physiology, this paper will offer a richer and more accurate picture of his views.
I presented earlier drafts of this paper at the London Ancient Science Conference in February 2017 and at the Annual Meeting of the Society for Ancient Greek Philosophy in October 2017. I am grateful for the feedback from those audiences and for the helpful comments of Patrick Finglass and the anonymous reviewer at CQ, as well as to Mark Schiefsky for early conversations. All translations are my own.
1 E.g. Littré, É., Œuvres complètes d'Hippocrate (Paris, 1839–61), 1.222–3Google Scholar; Kapferer, R., Die anatomischen Schriften, die Anatomie, das Herz, die Adern, in der Hippokratischen Sammlung (Stuttgart, 1951), 15–55Google Scholar; Ghalioungui, P., ‘The West denies Ibn Al-Nafis's contribution to the discovery of the circulation’, in Jundi, A.R. and Hasan, H.M. Zahoorul (edd.), Second International Conference on Islamic Medicine (Kuwait City, 1982), 299–304Google Scholar.
2 E.g. Harris, C.R.S., The Heart and Vascular System in Ancient Greek Medicine (Oxford, 1973), 109Google Scholar on Praxagoras’ ‘tragical mistake . . . which more than almost any other prevented the discovery of the circulation’ and Shaw, J.R., ‘Models for cardiac structure and function in Aristotle’, JHB 5 (1972), 355–88CrossRefGoogle ScholarPubMed, at 355–6, who, after framing Aristotle as ‘ignorant of both circulation and respiration’, laments that his interpretation of the heart's function was ‘so mistaken and confused . . . that it is impossible to get a clear picture from his authentic works’.
3 Harris (n. 2), 1.
4 Boylan, M., and, ‘The digestive “circulatory” systems in Aristotle's biology’, JHB 15 (1982), 89–118Google ScholarPubMed, at 118. Compare Ogle, W., Aristotle on The Parts of Animals. Translated with Introduction and Notes (London, 1882)Google Scholar, 193 n. 5: ‘in calling the heart origin or centre of the vessels, A. implies two things: firstly, that it is the place where the blood is made; and, secondly, the place whence blood, when thus made, is propelled into the vessels, blood going from it, but none returning to it’; Lanza, D. and Vegetti, M., Opere biologiche di Aristotele (Turin, 1971), 550Google Scholar: ‘non c’è communque in quest'opera alcuna idea della circolazione del sangue, il cui flusso è sostanzialmente a senso unico, dal centro alla periferia’ (cf. at 648); Harris (n. 2), 135: ‘blood flows from the heart to the other parts of the body, it does not come to the heart from elsewhere. No circulation for the Master of those that Know’; Siegel, R.E., ‘Principles and contradictions in the evolution of Hippocrates’, Aristotle's and Galen's doctrines of respiration and blood flow’, Episteme 9 (1975), 171–88Google Scholar, at 175: ‘all the blood was used up peripherally and never returned’; van der Eijk, P., Aristoteles. De insomniis, De diuinatione per somnum (Berlin, 1994), 83–4Google Scholar: ‘Aristoteles fast nirgends von einem Rückfluß des Blutes zum Herzen spricht: im Gegenteil, das Blut kommt aus dem Herzen hervor und verteilt sich zu den Organen und Geweben, denen es zu Nahrung dient; von einer Rückkehr des Blutes findet sich bei Aristoteles sonst nirgends eine Spur’; Lennox, J.G., Aristotle On the Parts of Animals I–IV. Translated with Introduction and Commentary (Oxford, 2001)Google Scholar, 257 (ad loc.): ‘Aristotle gives no indication why he is so sure that blood flows from the heart into the blood vessels but not vice versa’; Louis, P., Aristote. Histoire des Animaux (Paris, 2002 2)Google Scholar, 77 n. 1 (ad loc.): ‘comme on le voit Aristote ne soupçonnait pas le méchanisme de la circulation sanguine’; Oser-Grote, C.M., Aristoteles und das Corpus Hippocraticum. Die Anatomie und Physiologie des Menschen (Stuttgart, 2004), 125Google Scholar: ‘vom Herzen also . . . ergießt sich alles Blut in die Adern, aber keinerlei Blut fließt wieder in dieses zurück’; Zierlein, S., ‘Aristoteles’ anatomische Vorstellung vom menschlichen Herzen’, Antike Naturwissenschaft und ihre Rezeption 15 (2005), 43–71Google Scholar, at 47: ‘[das Herz] gebe Blut in die Adern, ohne irgendwoher Blut zu empfangen’.
5 Hist. an. 513a22; Part. an. 665b14–21; Resp. 474b8.
6 Harris (n. 2), 121–76 summarizes the various attempts, now updated by Zierlein (n. 4), which provides an analysis of the differences among Aristotle's accounts and their discrepancies from the actual anatomy. See now Dean-Jones, L., ‘Aristotle's heart and the heartless man’, in Wee, J.Z. (ed.), The Comparable Body: Analogy and Metaphor in Ancient Mesopotamian, Egyptian, and Greco-Roman Medicine (Leiden, 2017), 122–41Google Scholar, which proposes a new interpretation of these texts on a fetal model.
7 Hist. an. 496a4–34, 513a27–b7; Part. an. 666b1–667a11; Somn. 458a15–19.
8 Following the text in Balme, D.M., Aristotle Historia Animalium Volume I Books I–X: Text. Prepared for publication by Allan Gotthelf (Cambridge, 2002)Google Scholar.
9 Text from Balme (n. 8), except for the final sentence, which is emended along the lines of the popular conjecture found in two sixteenth-century editions. For a detailed discussion of the translation of this passage, see Bubb, C., ‘Hollows in the heart: a lexical approach to cardiac structure in Aristotle’, Sudhoffs Archiv 103 (2019), 128–40CrossRefGoogle Scholar with a note on the emended sentence at n. 7.
10 Part. an. 666b21–34: ἔτι δὲ βέλτιον τρεῖς εἶναι τὰς κοιλίας, ὅπως ᾖ μία ἀρχὴ κοινή⋅ τὸ δὲ μέσον καὶ περιττὸν ἀρχή.
11 That is, in keeping with the cardiac description in Part. an., each chamber connects to its own vessel, i.e. the great vein to the right and the aorta to the left; this is the standard interpretation (cf. Hett, W.S., Aristotle On the Soul, Parua Naturalia, On Breath [Cambridge, MA, 1957], 343Google Scholar; Lloyd, G.E.R., ‘The empirical basis of the physiology of the Parua Naturalia’, in id., Methods and Problems in Greek Science [Cambridge, 1991], 224–47Google Scholar, at 231; Gallop, D., Aristotle On Sleep and Dreams [Warminster, 1996], 83)CrossRefGoogle Scholar. Recently both Zierlein (n. 4), 51 and Dean-Jones (n. 6), 136 have independently argued that it should be interpreted as both vessels connecting with both chambers, but this renders the anatomy quite complicated and is at odds (as Zierlein indeed highlights) with the statement at Part. an. 666b27–9 that each of the two vessels should have its own, distinct, origin. The Greek by no means demands this alternative and more difficult translation; compare, for example, Hist. an. 515a1–2 and 564a20–4, where this same grammatical construction should clearly be interpreted in the way I suggest.
12 As my hybrid approach to cardiac anatomy here indicates (as will the soon-to-follow treatment of the blood vessels), Aristotle approaches the details and workings of the cardiovascular system in a scattershot and sometimes self-contradictory way. It is therefore worth considering whether it is reasonable to hope to put together one definitive model of blood flow that he consistently applies across all of the texts. While I am cautious of attempting to present here a positive model for how precisely he conceived of the flow of blood in the body in every instance—such a thing is surely not feasible at any great level of detail—the evidence from across the corpus appears to uniformly indicate that, whatever his model is, it is consistently not compatible with a unidirectional flow of blood out of the heart. (Note that I have not included in Figure 1 the ‘perforations’ into the lung—Aristotle presents these perforations as allowing for the passage of air rather than for that of blood [Hist. an. 495b12–16, 496a31–2], making them irrelevant to the present discussion.)
13 Some interpreters have suggested that Aristotle also conceived of pulmonary vessels that directly connect the heart to the lungs (Harris [n. 2], 154–8 provides an overview of the main arguments). This is by no means certain—indeed, the passage quoted in the subsequent note would rather seem to deny it—but, even if it were the case, it would not materially change the argument presented here, so I have left the rather vexed question of pulmonary blood flow, which I address in more detail in Bubb (n. 9), to the side.
14 Part. an. 667b15: αἱ δὲ λοιπαὶ τούτων ἀποφυάδες εἰσίν.
15 The main description of the paths of the great vein and aorta is found at Hist. an. 513b12–515a15; additional information occurs at Hist. an. 496b29–497a5; Part. an. 670a14–18, 672b7, 677b36–678a26; and Gen. an. 738a10–27.
16 In Hist. an. Aristotle positively asserts that there are no connections between the aorta and the liver and spleen (514b28–9) or between the great vein and the uterus (515a5–7). However, in Part. an. he appears to claim that there are connections between both vessels and the liver and spleen (670a14–18), though it should be noted that, while the flow of ideas in this passage favours this interpretation (see, for example, the translation in Lennox [n. 4], 64 [ad loc.]), Louis (n. 4), 88–9 has tried to reconcile the account here with that in Hist. an. by assigning these connecting offshoots of the two vessels rather to the kidneys, which are also mentioned parenthetically in this sentence. Similarly, and less ambiguously, Aristotle connects both vessels to the uterus at Gen. an. 738a10–12.
17 On the heart as the final and most important organ of the digestive system, see Juv. 468b31–469a10.
18 See especially Part. an. 650a32–b1, 651a12–17; Gen. an. 786a35–b6; Resp. 474a25–b9.
19 On the references to this text, together with a theory for its absence from the modern corpus, see Louis, P., ‘Le traité d'Aristote sur la nutrition’, RPh 26 (1952), 29–35Google Scholar.
20 Part. an. 675b29–36: μεταβάλλει καὶ οὔτ’ ἔτι πρόσφατος οὔτ’ ἤδη κόπρος.
21 Part. an. 678a1–3: πλῆρες ὂν φλεβῶν πολλῶν καὶ πυκνῶν, αἳ τείνουσιν ἀπὸ τῶν ἐντέρων εἴς τε τὴν μεγάλην φλέβα καὶ τὴν ἀορτήν.
22 Part. an. 672b18; Insomn. 462b6; Juv. 469b31; Resp. 480a10; Somn. passim.
23 Compare Mete. 341b7–14, 357b25–7, 369a14–16, 378a19–20. Aristotle's characterization of this digestive substance as an exhalation is further tightened by his likening its movements to those of rain (see Passage 9 above), which is a meteorological condition driven by the evaporation and condensation of these exhalations (Mete. 346b32–3, 358a20–6, 359b35–360a17).
24 Nevertheless, this passage is usually interpreted and/or translated to indicate that blood formation occurs in the vessels as well as in the heart; see, for example, Ogle (n. 4), 203 n. 9; Hett (n. 11), 335; Lanza and Vegetti (n. 4), 1153; Harris (n. 2), 158; and Gallop (n. 11), 75. Indeed, Manuli, P. and Vegetti, M., Cuore, sangue, cervello: biologia e antropologia nel pensiero antico (Milan, 1977), 144–5Google Scholar cite this passage as proof of an early hemocentric theory in Aristotle that was later firmly but incompletely erased by the cardiocentrism of Parts of Animals; they cite Part. an. 668b8–9 as another example of a trace of it, but that passage refers to the secondary concoction of already concocted blood into residues (in this case sweat) rather than to the concoction of nutriment into blood.
25 Somn. 458a15–16: παντὸς δὲ τοῦ αἵματος ἀρχή, ὥσπερ εἴρηται καὶ ἐνταῦθα καὶ ἐν ἄλλοις, ἡ καρδία.
26 This is the approach of, for example, Lonie, I.M., ‘Erasistratus, the Erasistrateans, and Aristotle’, BHM 38 (1964), 426–43Google ScholarPubMed, at 437 and Althoff, J., Warm und kalt, flüssig und fest bei Aristoteles. Die Elementarqualitäten in den zoologischen Schriften (Stuttgart, 1992), 90Google Scholar.
27 Philo, Spec. leg. 1.216.
28 Anon. Lond. 34.46–7. Asclepiades was active in the first century b.c.; the papyrus dates to the first century a.d. (see D. Manetti, Anonymus Londiniensis. De Medicina [Berlin, 2011], ix).
29 Shaw (n. 2), 379–80 is quite enthusiastic about the possibility of discrediting sections of On Sleep, citing a rather more cautious Ogle (n. 4), 200 n. 26.
30 On ἐκ in compounds, see LSJ s.v. C.2: ‘to express completion, like our utterly’. For the contemporary use of αἱματόειν, see Thuc. 7.84.5; Eur. Supp. 77, Phoen. 1149, Bacch. 1135; Ar. Pax 1020; Xen. Cyr. 1.4.10.
31 Hist. an. 520b10–19. Cf. Hist. an. 511b11–20; Part. an. 654a32–b11; Gen. an. 740a22–4.
32 In addition to the passages given here, there is similar language at De an. 444a12–13.
33 Somn. 456b18–22: ἐκ τῆς περὶ τὴν τροφὴν ἀναθυμιάσεως γίγνεται τὸ πάθος τοῦτο⋅ ἀνάγκη γὰρ τὸ ἀναθυμιώμενον μέχρι του ὠθεῖσθαι, εἶτ’ ἀντιστρέφειν καὶ μεταβάλλειν καθάπερ εὔριπον.
34 Somn. 456b22–8, particularly translated at 25 (τό τε ὑγρὸν καὶ τὸ σωματῶδες, ‘both liquid and particulate’) and 27 (ῥέψῃ κάτω, ‘sinks downwards’), 457b21 (διὰ τῶν φλεβῶν, ‘through the veins’; cf. 457a11–27), 458a27–8 (ἐπὶ τὸ πρῶτον αἰσθητήριον, ‘upon the primary aisthētērion’).
35 It does not seem plausible that both of these terms might be describing fully concocted blood. Aristotle would not characterize blood as an exhalation; the former is always a liquid, whereas the latter is always a vaporous or smoky substance, often explicitly contrasted with the liquid state. It seems more probable that he is here describing a flow of blood, perhaps made frothy by the addition of the exhalation, rising to the head, where the entire mixture cools and condenses, falling back down as an unqualified, though still not completely concocted, liquid.
36 Somn. 458a21–2: τὸ γίγνεσθαι ἀδιακριτώτερον τὸ αἷμα μετὰ τὴν τῆς τροφῆς προσφοράν.
37 Somn. 458a2–5: ἡ μὲν περιττωματικὴ ἀναθυμίασις εἰς φλέγμα συνίσταται (διὸ καὶ οἱ κατάρροι φαίνονται γιγνόμενοι ἐκ τῆς κεφαλῆς), ἡ δὲ τρόφιμος καὶ μὴ νοσώδης καταφέρεται συνισταμένη.
38 Hist. an. 521b3: γίνεται δὲ πεττομένων ἐξ ἰχώρων μὲν αἷμα, ἐξ αἵματος δὲ πιμελή . . . ἰχὼρ δ᾽ ἐστὶν ἄπεπτον αἷμα, ἢ τῷ μήπω πεπέφθαι ἢ τῷ διωρῶσθαι; Part. an. 651a17–18: ἰχὼρ δ’ ἐστὶ τὸ ὑδατῶδες τοῦ αἵματος διὰ τὸ μήπω πεπέφθαι ἢ διεφθάρθαι.
39 Somn. 458a21–2: διὰ δὲ τὸ γίγνεσθαι ἀδιακριτώτερον τὸ αἷμα μετὰ τὴν τῆς τροφῆς προσφορὰν ὕπνος γίγνεται.
40 Hist. an. 521a33. Indeed, in animals with insufficient heat to effect fully sanguifing concoction, the ichor simply takes over throughout the system as counterpart of the blood (cf. Hist. an. 489a23, 511b4).
41 Hist. an. 521a13: ἐξυγραινομένου δὲ λίαν νοσοῦσιν⋅ γίνεται γὰρ ἰχωροειδές, καὶ διορροῦται οὕτως ὥστε ἤδη τινὲς ἴδισαν αἱματώδη ἱδρῶτα. Compare to Hist. an. 586b32, 630a6, 632a18, where ichor runs out of wounds.
42 Juv. 469b6–13: ἐργάζεται γὰρ καὶ πέττει τῷ φυσικῷ θερμῷ τὴν τροφὴν πάντα, μάλιστα δὲ τὸ κυριώτατον.
43 Part. an. 670a19–21. Indeed, the descriptions at Hist. an. 496b29–33 and, depending on how it is interpreted (see n. 16 above), possibly also the Part. an. passage immediately preceding this one emphasize that the liver and spleen are not connected to the aorta at all, meaning that they would miss out on half of the nutritive exhalations drawn from the intestines. Boylan (n. 4) (cf. M. Boylan, The Origins of Ancient Greek Science. Blood—A Philosophical Study [New York and London, 2015]) repeatedly and confidently asserts that the liver and spleen are the next step in the digestive process after the food exits the digestive tract, but there is absolutely no textual support for this claim (as, indeed, he largely concedes in two footnotes: [n. 4], 103 n. 31 and 110 n. 40). Beyond this lack of positive evidence, the description of the vascular system, as I have argued, tends to prohibit such an arrangement. Boylan's only plausible evidence in his assertion that the spleen is prior to the heart on the path of digestion is the passage at Part. an. 670b4–6, where Aristotle describes how the spleen ‘draws to itself the watery residue out of the stomach and, being bloody, is able to concoct it’ (ὁ γὰρ σπλὴν ἀντισπᾷ ἐκ τῆς κοιλίας τὰς ἰκμάδας τὰς περιττευούσας, καὶ δύναται συμπέττειν αἱματώδης ὤν); this, however, is a description of the spleen receiving non-nutritive residue in direct contrast to nutritive exhalation. The concoction here is not a digestive but a residual concoction.
44 An alternative way of dealing with this statement is to assume that the liver and spleen aid in concoction only indirectly, by means of making the stomach and intestines hotter, as seems to be the case for the omentum (Part. an. 677b30–4).
45 Part. an. 666a11–13: ἔτι δ’ αἱ κινήσεις τῶν ἡδέων καὶ τῶν λυπηρῶν καὶ ὅλως πάσης αἰσθήσεως ἐντεῦθεν ἀρχόμεναι φαίνονται καὶ πρὸς ταύτην [i.e. τὴν καρδίαν] περαίνουσαι; 653b5–8: τὸ γὰρ ἐν τῇ καρδίᾳ θερμὸν καὶ ἡ ἀρχὴ συμπαθέστατόν ἐστι καὶ ταχεῖαν ποιεῖται τὴν αἴσθησιν μεταβάλλοντός τι καὶ πάσχοντος τοῦ περὶ τὸν ἐγκέφαλον αἵματος.
46 Somn. 458a17–19: ἐκείνων δ’ ἑκατέρα δέχεται ἐξ ἑκατέρας τῆς φλεβός, τῆς τε μεγάλης καλουμένης καὶ τῆς ἀορτῆς⋅ ἐν δὲ τῇ μέσῃ γίγνεται ἡ διάκρισις; Lloyd (n. 11), 243 n. 81 briefly admits the troubling implications of this quote in contrast to our original passage from Part. an. 666a6–8; Shaw (n. 2) also signals it as potentially problematic, but dismisses it as ‘possibly spurious’ (at 355 n. 1) and asserts that, at the very least, there is ‘no possible way to align it with the general cardiology to be found in other Aristotelian works’ (at 388); Althoff (n. 26), 90 suggests that it is not blood that is in question here but nutritive matter which has almost become blood, though he acknowledges that this interpretation leaves him with an unresolved traffic jam as the new blood leaves the heart (cf. Zierlein [n. 4], 46 n. 7 and Oser-Grote [n. 4], 125). Insomn. 461b11–13: ὅταν γὰρ καθεύδῃ, κατιόντος τοῦ πλείστου αἵματος ἐπὶ τὴν ἀρχὴν συγκατέρχονται αἱ ἐνοῦσαι κινήσεις, αἱ μὲν δυνάμει αἱ δὲ ἐνεργείᾳ.
47 Boylan (n. 4), 116.
48 One might imagine the vascular system as a pot of custard cooking on a stove. At intervals, the chef might add some new uncooked milk and egg; this new raw addition would flow through and with the already cooked custard as it was stirred, only gradually achieving the temperature required to be fully cooked as it passed close to the heat source.
49 Resp. 479b31–3: ἔστι δ’ ὅμοιον ζέσει τοῦτο τὸ πάθος⋅ ἡ γὰρ ζέσις γίνεται πνευματουμένου τοῦ ὑγροῦ ὑπὸ τοῦ θερμοῦ.
50 Peck, A.L., Aristotle Generation of Animals (Cambridge, MA, 1963), lxiv, 592–3Google Scholar; Harris (n. 2), 136–7 (citing Peck); and Boylan (n. 43), 56, 64–5 are also sympathetic to this view; Freudenthal, G., Aristotle's Theory of Material Substance: Heat and Pneuma, Form and Soul (Oxford, 1995), 122Google Scholar stops short of suggesting that the moment of pneumatization is equivalent to that of blood formation, but his theory is certainly consistent with it.
51 He says at Gen. an. 737b30 that ‘each [residue] is borne to its appropriate place without the pneuma compelling it nor any other such cause forcing it’ (φέρεται γὰρ ἕκαστον εἰς τὸν οἰκεῖον τόπον οὐθὲν ἀποβιαζομένου τοῦ πνεύματος οὐδ’ ἄλλης αἰτίας τοιαύτης ἀναγκαζούσης); Boylan (n. 4), 117 argues that this discussion of the motion of residues is not applicable to blood precisely because blood can be differentiated from residues in light of its pneumatization—thus suggesting that blood is compelled by pneuma. However, given that this passage occurs in the context of discussing the specific residue semen, which is formed from fully concocted blood and is most pointedly endowed with pneuma, I am hesitant to put too much faith into that line of reasoning, neat though it is.
52 Freudenthal (n. 50), 128–30 similarly suggests that it is the pneuma inherent in the blood that contains the vital heat and is thus naturally subject to upward motion.
53 Somn. 458a13–15: ἔστι δὲ λεπτότατον μὲν αἷμα καὶ καθαρώτατον τὸ ἐν τῇ κεφαλῇ, παχύτατον δὲ καὶ θολερώτατον τὸ ἐν τοῖς κάτω μέρεσιν.
54 For the transformation of blood into flesh and other parts of the body, see Part. an. 668a1–33; Gen. an. 743a1–28, 744b12–28; and Gen. corr. 322a5–16.
55 Aristotle distinguishes between ‘useful’ and ‘useless’ residues at Gen. an. 735a4–8, but these categories do not quite map on to the chronological flow of digestion that I am attempting to capture here.
56 Part. an. 677a12–15; Gen. an. 725a14–18.
57 Part. an. 651a21–4, 651b20–35; Gen. an. 726b2–5, 727a2–4, 777a8–9.
58 This is what seems to happen with the kidneys (Part. an. 672a1–13) and the omentum (Part. an. 677b25–8).
59 Gen. an. 725a11–21, 726b2–12, 726b14–15.
60 Gen. an. 718a6–7.
61 Gen. an. 725a24–7, 726b3–15.
62 On the localized collection of residues, see Gen. an. 725a34–b4.
63 Fat: Gen. an. 726a3–7; Part. an. 651b12–17; large animals: Gen. an. 725a32–4; growth: Gen. an. 725b22–5.
64 On the link between post-coital exhaustion and blood, see Gen. an. 725b7–9 and 726b12–13; for the full-bodied nature of the exhaustion, see Gen. an. 721b15–18.