In line with his strict distinction between processes according or contrary to nature, in Galen’s comprehensive system there is less room for ambiguities: health and disease are clearly separated, and disease is characterised by a locus affectus, a specific type of imbalance, and a quantitative degree of imbalance.

Boundaries between health and disease: natural versus non-natural sleep

Naturally, this author recognised healthy sleep and a non-healthy state, kôma, which could be wakeful or drowsy. The normal process is described in On the distinction of diseases:

This is the passage mentioned above where sleep is described as a quiet activity: in the dark, without external stimuli (which would suggest that observed sleep was an unusual situation). On a more physiological note, disconnection from the environment (tôn exôthen) is a crucial feature of sleep. Apart from perceptions – which had appeared in Aretaeus – Galen highlights the lack of movement. Considering that both are capacities of the psuchê in Galen’s theoretical model, it is not surprising that the unhealthy kind of sleep will be considered together with the conditions that affect the ruling part of the soul (located in the brain):

In a nutshell, non-natural sleep occurs when the psuchê is either affected in the aisthêtikon or the phantastikon (which in turn belongs to the hêgemonikon). Hence, the locus affectus is clear, and with it, the site to which the treatment should be applied:

Sleep and wakefulness as a continuum

The consequence of the above-mentioned disturbances is designated as kôma or kataphora, namely, impaired consciousness:

The transition between abnormal sleep and wakefulness is so blurred that in conditions with impaired consciousness one cannot really tell one from the other. As a matter of fact, Galen is suggesting that it makes no sense trying to distinguish between them. In contemporary terms we would construe the concept as a single condition (kataphora, kôma, impaired consciousness) with various manifestations (drowsiness, hallucinations, confusion). Furthermore, such a view actually implies that somnolent and wakeful impaired consciousness are two presentations of a similar phenomenon. This stance is not only in utter contradiction to Celsus, who conceived sleep as an all-or-nothing phenomenon (where patients could only be either awake or asleep), but it also challenges the Hippocratic authors and Aretaeus. Indeed, although all of them did admit some grey areas with fuzzy edges between wakefulness and sleep, they nonetheless attempted to associate such conditions either with one or the other (as discussed within the sociological commentary, the specific treatment for each category required that kind of clarity in the classification).Footnote ²

The blurred boundaries, however, are not limited to the distinction between delirium and sleep. A passage where Galen contrasted certain diseases of the hêgemonikon with sunkopê illuminates the way in which he understood the relationship between the three prototypes of impaired consciousness:

First of all, the fact that Galen needed to contrast conditions with impaired hêgemonikon and phantastikon – such as epilepsy, torpor, kôma, catalepsy and delirium – with cardiacum (total loss of consciousness) suggests that he perceived them to be easily confused conditions.Footnote ³ In terms of their specific links, the three prototypes of impaired consciousness may well originate in the stomach, but they all ultimately affect a part of his tripartite soul: the psuchê.Footnote ⁴ The difference is that whereas the latter has sympathy towards the archê in the heart (spirited psuchê), all the others have it towards the brain (rational psuchê). The kind of disease that develops depends on where specifically the sympathy goes.

In other words, the problem begins in the stomach, but it is the second stopover that will determine the kind of affection: if it is the rational soul, it will trigger diseases of the hêgemonikon (with drowsy or hyperactive impaired consciousness), whereas if the spirited soul receives the sympathy, it will trigger a sunkopê (total loss of consciousness). The above shows that although the psuchê was affected in all the situations that we nowadays consider as impaired consciousness, there were nuances. As we shall see in Part III of this book, Galen consistently attributed delirium and sleep to the hêgemonikon, whereas fainting was sometimes related to a different part of his tripartite Platonic soul. When the emphasis was put on the loss of movement and perceptions that fainting causes, the affection of the hêgemonikon in the brain was emphasised. When, on the other hand the mechanism of swoons (the loss of blood) was under discussion, the attention was diverted towards the spirited soul in the heart, which carries the innate heat.

Levels of consciousness

For certain, Galen offers explicit speculation on the gradable physiology of both healthy and pathological sleep. As far as the former is concerned,

Galen explicitly conceives different levels of disconnection that manifest in progressive depths of sleep, and they depend on the quantity of perception capacity flowing from the archê (in the brain) towards the senses.

Concerning the abnormal kind of sleep, I have already pointed out that in Galen’s system, the antithetic character of the qualities (cold–hot, dry–moist) enables a rational explanation for opposite symptoms (such as insomnia–drowsiness). We should now add that the gradual nature of such qualities allows – and even encourages – reflection upon their intensity. For certain, qualities admit degrees, which makes it relatively easy for a doctor to correlate levels of heat, coldness, dryness or moistness to a corresponding severity of the compromise:

Clearly, Galen’s system contemplates this perfect continuum between antithetical symptoms, which are correlated with opposed qualities. The same rationale underpins the polarity that contrasts lethargy with phrenitis. Consistently throughout his works, the former is hypoactive and caused by the coldest and wettest mixtures, whereas the latter is hyperactive and the result of the hottest and driest kraseis:

Although Galen does not explicitly link these phenomena to the quantitative aspect of his humoural theory, he does illustrate his explanations with the same examples as those he had used to explore the gradability of the theory. Therefore, it is not unreasonable to think that – also in this regard – he did consider the levels of consciousness to be parallel to the degrees of the qualities: somnolenta igitur, quantum ad praesens, ipsis litargicis insidet, insomnem vero, que freneticis supervenit, temptandum distinguere. (‘Therefore, somnolent [kataphora] – which determines the degree of lethargy itself – should be distinguished from sleepless [kataphora], which can befall phrenitic patients’).Footnote ⁵ In other words, impaired consciousness (kataphora) can manifest with symptoms that extend from sleep – at the hypoactive end of the spectrum – all the way through to wakefulness, with a whole range of intermediate states. In such states, presumably, the degrees of heat, coldness, moistness and dryness determine the severity of the delirium or the depth of the sleep, which are ultimately two sides of the same coin.

From a less pathophysiological point of view, it is interesting to place this concept of correlations between depths of sleep and seriousness of ailments within a broader context and amid the non-medical discourses. There is an explicit philosophical formulation in Aristotle’s Generation of animals:

If we consider that death is often the end stage of serious illnesses, and that according to these doctors becoming progressively sick manifests by becoming progressively drowsy, one can see how these closely connected ideas have possibly interacted and interfered with each other. Indeed, the liminality of sleep between life and death seems to have been deeply ingrained in ancient discourses (well beyond archaic epic poetry). It penetrated medicine to such an extent that even Celsus, who did not conceive a progression in the levels of consciousness, still regarded sleep as a sign of imminent death: eadem mors denuntiatur … ubi adsidue dormit (‘Death itself is announced … when one sleeps uninterruptedly’).Footnote ⁶

To sum up, the way in which these authors tackled sleep illustrates how strict definitions and clear boundaries sometimes obscure phenomena, rather than help to explain them. Celsus’ strict separation between wakefulness and sleep prevented him from considering intermediate conditions and stages that were present in other contemporary treatises. Furthermore, although he was interested – as most other post-Hellenistic sources – in the relationship between perceptions and reality, he only discussed the topic in connection with delirium but not with sleep (as Aretaeus and Galen did), thereby leaving out questions about the reality of dreams. In a similar manner, Galen’s clear distinction between health and disease did not allow him to see the gradual transition between both stages. He seems to have clearly understood the progression in the seriousness of illnesses, the related nature of wakefulness and sleep, and even the subtle transition between delirium and drowsiness, but not the link between healthy and disturbed sleep. Paradoxically, both authors took such boundaries for granted and made no effort to define where exactly they set them. Celsus did not explain how to distinguish wakefulness from sleep, nor did Galen clarify where healthy sleep ended and disturbed sleep began. On the contrary, those limits remain as purely theoretical constructions in the texts, which are only self-evident when considering the prototypical extreme situations, but are much less obvious in the intermediate stages.

This lack of explanation is perhaps due to the fact that the exact location of such limits was not established by medicine but by the culture of that time. If – as Williams states – every society organises and schedules the sleep of its members, we can suggest that the medical discourse is only providing explanatory models and solutions (in the form of treatments) for situations where the transgression of social rules is construed as disease.Footnote ⁷ Ultimately, the amount of sleep regarded as normal, the pattern of sleep during night or day and the level of sleepiness acceptable in an interaction are socially regulated conventions.Footnote ⁸ Taking this idea a step further, the whole concept of consciousness that emerges from this analysis of sleep could be regarded as the way in which these medical writers accommodated some medical theoretical frameworks to the various non-medical discourses on sleep available in their time and place.

Galen’s approach to HOFs, the mind and their terminology

Unlike the previous authors, where the idea of mind and the organisation of HOFs had to be deduced from hints in the descriptions, Galen was very explicit about it and delimited a systematic, coherent and consistent division of the different domains involved in the workings of the mind:

In this passage, Galen is establishing clear boundaries of what constitutes ‘the psychic’, what its sub-divisions are and what are their corresponding activities or functions. It is within these theoretical limits that he will later discuss all the conditions that we nowadays consider as wakeful and drowsy impaired consciousness. We could be tempted to regard the activities of the hêgemonikon as similar to our current medical idea of consciousness.Footnote ¹⁰ However, other texts present minor variations in terminology and some nuances in the concepts, which prevent such a correspondence. In a more philosophical work, for instance, Galen states that ἡ λογιστικὴ ψυχὴ δυνάμεις ἔχει πλείους, αἴσθησιν καὶ μνήμην καὶ σύνεσιν ἑκάστην τε τῶν ἄλλων (‘the rational (logistikê) psuchê has several capacities: perception, memory and understanding (sunesin) of each of the others’).Footnote ¹¹ When comparing the two extracts there appears to be some overlap and simplification between what he had defined as ‘psychic activities’ and what he is designating as ‘the capacities of the rational psuchê’. In yet another treatise the hêgemonikon is the site where ἐπιστήμης τε καὶ δόξης ἁπάσης τε διανοήσεως (‘knowledge (epistêmê), all the judgement (doxa) and intellect (dianoêsis) are to be found’),Footnote ¹² and later on he states that αἱ μὲν τοῦ λογιστικοῦ τῆς ψυχῆς ἐνέργειαι καλείσθωσαν ἠγεμονικαὶ (‘the activities of the rational (logistikou) part of the psuchê should be called hêgemonikai [that is, belonging to the authoritative part]’).Footnote ¹³ Ultimately, although there are some discrepancies concerning what belongs to the rational psuchê in general and to the hêgemonikon in particular,Footnote ¹⁴ it seems that Galen is grouping together some HOFs, most of which are nowadays considered to belong in the sphere of consciousness.Footnote ¹⁵ Moreover, it could be argued that in this sense he remained remarkably consistent throughout his work. He considered all the diseases that affect these psychikai/hêgemonikai energeiai, or the logistikon tês psuchês to be related,Footnote ¹⁶ and he offered a comprehensive catalogue of them in his treatise On the distinction of symptoms:

Although there are other classifications throughout the corpus with minor variations, as well as certain conditions that are not mentioned here (which Galen nonetheless considered to belong in this group),Footnote ¹⁷ there is consistency in terms of the anatomical and physio-pathological understanding. All these conditions affect the brain (because it is the seat of the rational soul), and they all occur as a consequence of an imbalance in the krasis,Footnote ¹⁸ namely, an approach with evident advantages in terms of therapeutic conduct, for it explained diseases in a way that enabled Galenic medicine to successfully treat them.

Regarding the organisation of the mind, Galen’s fragmentation of the HOFs blurred several distinctions that we now make (because they were irrelevant to his therapeutic approach). Thus, by describing all these conditions as affections of the psuchê,Footnote ¹⁹ and classifying them according to the type of psychic activity disturbed (perception, motion or ruling part) and the kind of compromise (complete, partial or deviant), the edges between impaired consciousness (wakeful or drowsy) and mental illnesses become fuzzy, for they are both diseases where the intellectual (dianoêtikon) activities of the ruling part of the rational psuchê – the hêgemonikonFootnote ²⁰ – are damaged. Similarly, because the psuchikai energeiai are affected in delirium and mental illness, as well as in tetanus, epilepsy and the case of the youth with speechlessness and traumatic paralysis (already mentioned, Loc. Aff. CMG I.6: 284, 12–17. K.VIII: 50–1), the boundaries between what we now consider as neurological conditions, impaired consciousness and mental illness also become faint. In other words, although Galen subsumed the mental capacities within constructs that are broader than our idea of consciousness, he was able to clinically distinguish cases with impaired consciousness, and he did perceive an abstract notion to be compromised in such situations (albeit a notion comprised of more HOFs than we nowadays consider).

Concerning terminology, as Jouanna has remarked,Footnote ²¹ a parallel passage from On the causes of symptoms (II. 7. K.VII: 200–4) complements and introduces slight lexical nuances to this list. In this other version Galen calls môrôsis what he had previously designated as anoia, and defines it as a complete paralysis of the activities of the dianoêtikon. The partial impairment of such activities, which he had previously defined as môria and môrôsis, are now referred to as νάρκαι τοῦ λογισμοῦ τε καὶ τῆς μνήμης (‘reason and memory numbness’).Footnote ²² Interestingly, in this rendering he expands the notion of deliria (paraphrosunai) and includes some specific diseases such as phrenitis, mania and melancholikai paranoiai.

Undoubtedly, these passages reveal a fairly standardised and rather concise vocabulary. Galen’s use of terminology, therefore, is more in line with the post-Hellenistic authors than with the Hippocratic doctors, where we found an extensive use of partial synonymy. Although there was a certain instability (for example, between anoia/môrôsis when tackling the diseases of the dianoêtikon), in the last passages, his vocabulary reminds us of Aretaeus’: paraphrosunê seems to be the most common word for delirium (even if parakoptô is exceptionally used to describe similar phenomena).Footnote ²³ Paranoia in the comment on melancholia was used to designate the specific kind of delusion that characterised that condition. Finally, paralêrêsis – as in Aretaeus – is the word chosen to talk about the mental disturbance of old age (what we would nowadays call dementia): διὰ τί τοίνυν εἰς ἔσχατον γῆρας ἀφικνούμενοι παρελήρησαν οὐκ ὀλίγοι τῆς τοῦ γέρως ἡλικίας ἀποδεδειγμένης εἶναι ξηρᾶς; οὐ διὰ τὴν ξηρότητα φήσομεν ἀλλὰ διὰ τὴν ψυχρότητα (‘Why do most of those who reach extreme old age act foolishly (parelêrêsan), if old age has been demonstrated to be dry? We shall reply, not due to the dryness but to the coldness’).Footnote ²⁴ Once again, there is a humoural correlate that will guide the specific treatment of this clinical condition.