On the Sacred Disease

On the Sacred Disease is a short Hippocratic treatise arguing that epilepsy — the condition Greeks called the “sacred disease” — is not caused by divine intervention but by a natural disorder of the brain. Its opening pages attack the itinerant practitioners who treated the disease through purifications, dietary taboos, and prayers, accusing them of using the divine as a cover for ignorance. The brain hypothesis the author proposes in the second part of the text is the oldest surviving attempt to locate a specific mental phenomenon in a specific organ. The treatise is frequently cited as the founding document of Western naturalistic medicine, and Jouanna identifies it as the first time a rational medicine was “posited in express opposition to a religious and magical medicine.” That citation, however, requires qualification: the author did not replace divine causation with pure materialism. Nutton and others have noted that the author’s naturalism operated within a framework that still acknowledged the divine — redefined, not removed.

Authorship, Date, and Place in the Corpus

Like most Hippocratic treatises, On the Sacred Disease was written by an unknown author. The attribution to Hippocrates himself is conventional, not historical. The Hippocratic Corpus, as Nutton notes, was likely assembled at the Alexandrian library and first appeared as a complete printed collection only in 1526. (Nutton, 2023) The great majority of its constituent treatises, including this one, were written sometime between 450 and 350 BCE. (Nutton, 2023) Dating within that range is uncertain; the language and concerns of the text are consistent with the late fifth century.

The treatise sits alongside Airs, Waters, Places and Ancient Medicine as one of several Hippocratic texts concerned explicitly with demarcating legitimate medicine from both philosophical speculation and magico-religious practice. (Nutton, 2023) These texts were not simply describing medicine’s methods; they were making arguments about what medicine should be allowed to claim.

The Argument Against Divine Causation

The treatise opens with a claim that became famous in antiquity. In Pormann’s rendering: “I shall discuss the so-called sacred disease. In my view it is no more divine or sacred than any other disease, since it has its own nature and occasion; but people think it to be a divine thing because of their helplessness and its strangeness.” (Pormann (ed.), 2018) Ackerknecht’s paraphrase conveys the same stance: epilepsy “appears to me to be nowise more divine nor more sacred than other diseases, but has a natural cause from which it originates like other affections. Men regard its nature and cause as divine from ignorance and wonder, because it is not at all like other diseases.” (Ackerknecht, 1955) The argument proceeds in several moves.

First, the author accuses the magico-religious practitioners of acting from concealment. As Jouanna summarizes the passage, they “concealed and sheltered themselves behind superstition, and called this illness sacred, in order that their utter ignorance might not be manifest.” (Jouanna, 1999) The charge is not simply theological but professional: these men claimed special knowledge they did not possess.

Second, and more carefully, the author attacks the practitioners on their own terms. He does not simply deny that gods can affect human health; he argues that attributing disease directly to gods is itself impious. If a practitioner claims to be able to drive out a god or compel a deity through chants and charms, he is claiming power over divinity — a presumption the author finds theologically offensive. Nutton identifies this as the sharpest edge of the argument: “his attack is not directed against temples and shrines as such — for in them the decision to heal or not to heal is left to the divinity — but against those who claim to be able to drive out demons and compel the gods to do their will by means of chants and charms.” (Nutton, 2023)

Third, the author accepts that some of the practitioners’ cures may work — but denies the causal story they tell about them. As Nutton reads the passage: “he can accept the reality of some of his opponents’ cures, while at the same time denying the causal connection that they have asserted: a patient has been cured by the drugs or diet they prescribed, not by the will of the gods.” (Nutton, 2023) This is a precise logical move: separating the empirical fact of a cure from its causal explanation.

The author’s positive account of causation is stated with equal directness. The text declares: “This so-called sacred disease comes about from the same occasions as the rest of them, from things that go into and come out of the body, from cold, the sun, and from the changing and never-resting winds … Each [disease] has its own phýsis and dýnamis, and none are untreatable. Most are cured by the same things from which they arise … Whoever knows how to bring about wet and dry, hot and cold, in human beings can cure this disease too, if he can determine the appropriate times and what is beneficial, without purifications and magic.” (Pormann (ed.), 2018) As Pormann notes, this passage exemplifies the Hippocratic commitment to allopathy and the reduction of causal factors to the fundamental qualities of hot, cold, wet, and dry, while also affirming the pathological significance of phlegm and bile. (Pormann (ed.), 2018)

The author also provides a detailed and in some ways sympathetic account of the practitioners’ diagnostic system. They had developed a grid matching symptom varieties to specific deities: convulsions on the right side were attributed to the Mother of Gods; horse-like behavior (rearing, kicking) to Poseidon; passing excrement to Enodia; foaming at the mouth and kicking to Ares; nocturnal terrors and jumping from the bed to Hecate or heroes. (Jouanna, 1999) This was not random improvisation. It was a structured diagnostic framework, applied consistently. The author found it wrong, not incoherent.

The practitioners’ treatment regimen was similarly systematic. They combined religious purifications and incantations with dietary restrictions that overlapped with Orphico-Pythagorean interdicts: forbidding sea fish (especially red mullet, black-tail, hammer fish, and eel), the flesh of goats, deer, pigs, and dogs, the vegetables mint, leek, and onion, and the wearing of black garments. (Jouanna, 1999) The author treated these restrictions as evidence of concealed naturalistic reasoning: practitioners who say they can purify through supernatural means but then forbid specific foods and garments are implicitly acknowledging that diet and material conditions affect the disease.

The Brain Hypothesis

Having dismissed the divine etiology, the author advances an alternative: the sacred disease originates in the brain. The brain, he argues, is the organ responsible for intelligence, perception, and motion; when it is disordered by excessive phlegm, the characteristic symptoms of epilepsy follow. This places On the Sacred Disease in a specific debate within Hippocratic physiology. The two humors most prominently linked to disease causation across the Corpus were phlegm and bile, both visible and easily associated with illness; most Hippocratic authors worked with these two rather than the later canonical four. (Nutton, 2023) The text’s heavy reliance on phlegm as a pathological agent is consistent with this earlier, simpler framework.

The brain theory itself was not universally accepted in the Hippocratic period. Alcmaeon of Croton had proposed a version of it earlier in the fifth century, and some Hippocratic texts attributed intelligence to the heart rather than the brain. The author of On the Sacred Disease was taking a position in an active dispute, not simply recording settled doctrine.

Alcmaeon of Croton had proposed that sense organs were linked directly to the brain by channels, and that loss of sensation could result from these channels becoming blocked — an insight based in part on his knowledge of the optic nerve. (Nutton, 2023) His definition of health as the equal distribution of bodily forces and disease as the domination of any one of them established the paradigm of health-as-balance that dominated medicine into the nineteenth century. (Nutton, 2023)

The author grounded his argument in direct observation as a mode of validation. Sacred Disease 14 states: “If you cut open and observe … you will find” — and the conclusion the observation yields is that “it is not a god but the disease which injures the body.” (Pormann (ed.), 2018) The logic is demonstrative: anatomical inspection of the brains of epileptic animals would settle the causal question. Sacred Disease 16 extends this to a broader account of the brain’s role: the brain coordinates perception and transforms it into knowledge, such that “the eyes, tongue, hands and feet carry out what the brain knows.” (Pormann (ed.), 2018) This is the earliest surviving attempt in Western medicine to articulate the brain as the central organ of cognition and voluntary action.

What the author proposed was not a fully mechanistic account. He identified phlegm in the brain as the pathological agent, but his explanation of why phlegm accumulates and how it causes the specific symptom pattern of epilepsy drew on the same analogical reasoning that characterized Hippocratic physiology generally — concerned, as Nutton notes, “far less with structures than with processes,” using analogies from crafts and the surrounding world. (Nutton, 2023) There was nothing in the text resembling a modern neurological account.

Naturalism and Its Limits

Pormann notes that a few sentences from the treatise are “constantly paraphrased and selectively cited as proof of the ‘rational’ character of Greek medicine,” but that this rational aspect is exaggerated — both with regard to the treatise itself (where the author’s stance is arguably quite traditional) and to Greek medicine in general (where irrational attitudes persisted even in Galen’s time). (Pormann (ed.), 2018)

The standard reading of On the Sacred Disease positions it as a declaration of scientific independence from religion: the moment when Greek medicine expelled the divine from disease causation and founded Western naturalistic medicine on the principle that natural phenomena have natural causes. Ackerknecht called the opening passage the “Declaration of Independence” of Greek medicine. (Ackerknecht, 1955) Jouanna describes the text as the first explicit opposition of rational to religious medicine. (Jouanna, 1999)

This reading, while not wrong, is incomplete. The author did not claim that all diseases are entirely without divine dimension. A parallel passage in Airs, Waters, Places — the position that Jouanna identifies as the Hippocratic synthesis — declares that diseases “are all divine and all human”: no disease is more sacred than another, which means every disease participates equally in both the natural and the divine order. (Jouanna, 1999) The author of On the Sacred Disease was not arguing that epilepsy lacks any connection to the divine; he was arguing that it has no more such connection than any other disease, and that the claim to special divine involvement is what the charlatans used to excuse their ignorance.

Nutton’s analysis pushes further. The text’s attack, he argues, was directed not at religious healing as such but at itinerant freelancers who claimed personal power over gods — a very different thing from the institutional temple healing at Asclepian shrines. The Asclepian cult, by contrast, operated on the theologically respectable premise that the god made his own decisions about who to heal. The author of On the Sacred Disease was, in this reading, participating in the same process of institutional consolidation that the rise of the Asclepius cult represented: both were marginalizing magical freelancers and defining medical orthodoxy against a charismatic, unaccountable alternative. (Nutton, 2023) By 350 BCE, as Nutton notes, “barriers had arisen between medicine and magic that had been almost non-existent in the sixth century.” (Nutton, 2023)

The author’s naturalism was also, in one sense, a different kind of divine reasoning rather than its replacement. To say that epilepsy is a natural disease is also, in the Greek framework, to say that it falls under the regular governance of natural order — which was itself divine. The separation of divine from natural causation that seems obvious to post-Enlightenment readers was not available to a fifth-century Greek in the same form. As Nutton observes of the broader question, the interaction between medicine and religion in antiquity is better understood “as a process of negotiation, of defining and redefining their separate spheres of action,” not as a confrontation between secular rationalism and religious superstition. (Nutton, 2023)

Van der Eijk’s Theological Reading

The scholarly tradition that reads On the Sacred Disease as the founding document of secular naturalism has been challenged most systematically by Philip van der Eijk, whose analysis of the text’s “theology” proposes a more layered account of what the author was and was not claiming about the divine.(van der Eijk, Philip J., 2005) Van der Eijk’s central argument is that the author does not reject the divine character of the disease but redefines it: the disease is divine because it participates in nature’s fixed pattern of cause and effect, not because it is god-sent. (van der Eijk, Philip J., 2005)

The central revision van der Eijk offers concerns what “divine” means in the text. The author does not deny that the sacred disease is divine; he argues that it is divine in precisely the same way as every other disease — because it participates in the fixed, regular pattern of cause and effect that governs natural phenomena. Van der Eijk identifies two competing readings of the text’s claim: either diseases are divine because they are caused by climatic factors (heat, cold, winds) that are themselves divine, or diseases are divine in virtue of having a phusis — a definite character and a regular pattern of origin and growth — the connotations of theios here being “constant,” “unchanging,” “imperishable.”(van der Eijk, Philip J., 2005) Van der Eijk argues that the second interpretation is closer to the text, since the mention of phusis in the key passages occurs in the immediate context of the claim that epilepsy is no more divine than other diseases: it is exactly its “having a nature” that constitutes the disease’s divine character.(van der Eijk, Philip J., 2005)

This means the dominant scholarly reconstruction of a “naturalistic theology” in the text — identifying “the divine” with nature itself — rests on three questionable generalizations. It conflates calling a particular phenomenon divine in virtue of a specific characteristic with speaking about “the divine” (to theion) in a general and abstract way; it extrapolates from specific statements about one disease to a comprehensive theology the author never articulates; and it ignores other assertions in the treatise that sit uneasily with such a reading.(van der Eijk, Philip J., 2005) Nowhere in On the Sacred Disease does the author state that “Nature is divine,” nor is there an explicit rejection of divine intervention in natural processes as such.(van der Eijk, Philip J., 2005)

Van der Eijk’s reading also addresses a feature of the text that naturalistic interpretations tend to explain away: the author’s apparent personal religious conviction. In section 1.44–6 of the treatise, the author states that it is more likely that bodies are cleansed by gods than polluted by them, and that concerning the greatest moral transgressions, the divine purifies and sanctifies human beings. Van der Eijk reads this as genuine personal belief — the author believes in gods who grant humans purification of their transgressions and who are to be worshipped in temples through prayer and sacrifice.(van der Eijk, Philip J., 2005) The text is silent on whether these gods are anthropomorphic, but there is no textual evidence that the author rejected the notion of personal gods, and he explicitly holds it blasphemous that holy beings would send disease as a form of pollution.(van der Eijk, Philip J., 2005)

The attack on the magico-religious practitioners is, on this reading, not an attack on religious healing as such but on a specific religious transgression: the magicians claim to control gods through incantations, compelling divine obedience. This is what the author accuses of impiety (asebeia). The contrast is between magic — in which humans perform purification by making gods obey incantations — and religion proper, in which humans approach gods in temples and pray for help, with the god himself performing purification.(van der Eijk, Philip J., 2005) The Asclepian cult, which left the decision to heal entirely to the god, was not the author’s target; the freelance operators who claimed personal power over divine will were.

What van der Eijk proposes as the author’s primary purpose is not the proclamation of a naturalistic theology but the disengagement of epilepsy from the religious domain and the transfer of that domain to medicine. The naturalistic statements about divine disease are, on this reading, derogatory concessions rather than proclamations of a new metaphysics.(van der Eijk, Philip J., 2005) This compares the author’s move to Plato’s corrective criticism of traditional ideas about divine dispensation (theia moira) — modifying the concept without questioning divine dispensation as such.(van der Eijk, Philip J., 2005)

A residual tension remains in the text, and van der Eijk accepts it rather than resolving it. The author categorically rejects the idea that holy beings send diseases (labeling it blasphemous), then asserts ten lines later that diseases are divine in virtue of having a phusis. These two claims are in tension — the rejection of divine pollution and the affirmation of natural divinity operate in different registers. Van der Eijk treats this tension as characteristic of religious thought, including that of educated intellectuals in the Greek world, and as perhaps a consequence of the polemical character of the treatise.(van der Eijk, Philip J., 2005)

Van der Eijk also draws a structural comparison to Aristotle’s argument in On Divination in Sleep against god-sent prophetic dreams: both the Sacred Disease author and Aristotle use the unexpected distribution of a phenomenon — epilepsy falling across different types of people, prophetic dreams occurring among the simple-minded rather than the wise — as evidence against divine providence. The rhetorical strategy, not merely the conclusion, is shared across the two texts.(van der Eijk, Philip J., 2005)

The theological conclusions van der Eijk draws from the analysis are deliberately modest: the author of On the Sacred Disease believed in personal gods who purify moral transgressions; he found it blasphemous that such gods would send disease as pollution; he treated divine dispensation itself as unquestioned; and his naturalistic statements about the divinity of disease were made in a polemical context aimed at establishing medicine’s authority over epilepsy rather than at constructing a philosophical theology.(van der Eijk, Philip J., 2005) What he produced was not a declaration of secular independence but a particular negotiation — within Greek religious thought — over which actors had legitimate authority to handle which conditions.(van der Eijk, Philip J., 2005)

Reception

In antiquity, the text was read as part of the Hippocratic Corpus and was included in the canon of treatises considered authentic by Erotian in the first century CE. Its argument for natural causation became one of the touchstones by which Hippocratic medicine defined itself against competitors.

The modern reception has been shaped primarily by the desire to locate the origins of secular medicine. For Ackerknecht, writing in 1955, the opening passage of On the Sacred Disease was effectively the founding statement of the entire Western medical tradition — the moment at which Greek physicians broke from religious healing and established that diseases require natural explanations. This reading gave the text an importance it held, and arguably still holds, in medical education and medical history.

Jouanna’s more careful reading emphasizes the text’s specific polemical situation — a debate within fifth-century Greek culture about who was qualified to treat the sick and on what authority — and notes that Hippocratic rationalism was “not atheistic but redefined the divine as coextensive with the natural.” (Jouanna, 1999) Nutton’s revisionist framing is the most consequential correction to the standard view: the text was not establishing that medicine is independent of religion, but rather drawing boundary lines within the religious and healing landscape of its time.

The brain hypothesis, for its part, has been cited as an early anticipation of neurology — the first attempt to localize mental phenomena in the brain. Here too the retrospective framing obscures more than it reveals. The author had no anatomy, no dissection, and no model of neural function. What he had was a theory about phlegm, a visible substance whose accumulation in the head seemed consistent with what he observed in patients. His reasoning was coherent given what he knew; connecting it to modern neuroscience as a precursor requires more distance from the evidence than the text itself warrants.

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Editorial Notes

Gaps the encyclopaedia compiler flagged for future evidence work, collected from inline markers in the body and frontmatter.

Reception

On the Sacred Disease

Authorship, Date, and Place in the Corpus

The Argument Against Divine Causation

The Brain Hypothesis

Naturalism and Its Limits

Van der Eijk’s Theological Reading

Reception

See Also

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Editorial Notes

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