Tieleman has accurately remarked that Aristotle had set the agenda of topics regarding psychology questions to be addressed and that several philosophers followed his lead.Footnote ¹ We have seen throughout our discussion that a few doctors also addressed similar queries.

Schematically, the main issues under scrutiny – according to Tieleman’s reading of Aristotle – were the existence of the soul as something in itself, its substance (ousia), the number and the type of its powers and its localisation in the body. As we have been seeing, all the medical writers under scrutiny (including the pre-Aristotelian ones) took the existence of the soul for granted. All of them started from the assumption that there is a soul and that it is a major player in impaired consciousness. The case of Galen should, perhaps, be nuanced because even if he insisted on how obvious it was, he did provide proof of the soul’s existence in On the doctrines of Hippocrates and Plato. The substance was not a key issue, although some medical writers did attempt physiological explanations based on assumptions concerning the substance of the soul.Footnote ² The most important concern for all these authors was the type of powers, the organisation of those powers and their localisation in the body. In other words, most doctors did take a position on each of the philosophical debates concerning the psuchê, but they only addressed the issues that were relevant to their practice. Unlike philosophers, they did not feel the need to justify all their assumptions. Galen, again, is the exception in this regard because he took part in medical and philosophical discussions alike.

As far as total loss of consciousness is concerned, we have seen a unanimous understanding of this presentation as a near-death experience, which points towards an assimilation of the soul to a life force, as though during fainting the body was momentarily depleted of whatever kept it alive. Accordingly, we have seen that this ‘life force’, contained in the breath in the archaic literature (identified as psuchê and thumos), is represented among the Hippocratic doctors as a medicalised psuchê that temporarily abandons the body during swoons and permanently in death. Similarly, in Celsus’ On medicine, it is the irrational part – the anima – of his dichotomous soul that reversibly separates during fainting and permanently departs with death. In Aretaeus this vital power, which the body becomes deprived of during total loss of consciousness, is construed as a tangle of ideas such as the heat of life of the body, the tension, the pneuma (all of them vaguely linked to his ill-defined psuchê). Finally, in Galen we should add the nuance that although total loss of consciousness was not strictly at the boundary between life and death (for in his account the soul did not actually separate during swoons – only the pneuma did), he did consider that the separation of the psuchê from the body was synonymous with dying, thereby equating his tripartite Platonic soul to a lifegiving entity.

Regarding the role of the psuchê as an abstract notion that provides a unifying theoretical common ground to the different presentations of impaired consciousness, it could be argued that this is certainly the case for the Hippocratic doctors. Amongst them, the all-encompassing psuchê – affected during total loss of consciousness – subsumed other constructs such as sunesis, phronêsis, nous, compromised in wakeful and drowsy impaired consciousness. Also in Celsus, the twin concepts animus–anima explain the different presentations of the condition. Thus, the rational component, mens/animus/consilium, is altered in delirium, whereas as suggested above, the degree of separation of the irrational anima – subordinated to the former – determines whether the patient faints (complete separation) or simply sleeps (partial separation). The case of Aretaeus is slightly different, because although there are common pathophysiological phenomena often associated with the different forms of impaired consciousness, he did not elaborate a consistent notion of the soul in his extant work, and his scattered allusions to it are often contradictory. There is, however, a unifying abstract concept that appears to be compromised in all the presentations of impaired consciousness. In line with Aretaeus’ engagement with the debate around perceptions, it could be argued that aisthêsis plays in his argument a role similar to that of the soul in the other authors. This construct appears to be ubiquitously present and compromised in all these conditions: in swoons and sleep, perceptions are interrupted (more so in the former than in the latter, where pain can still be felt). In delirium, on the other hand, individuals perceive abnormal things while their thinking is intact (unlike other cognitive conditions – mental illness according to our current understanding – where the gnômê is compromised but perceptions are intact). In Galen, finally, the soul is again a common component of the different presentations of impaired consciousness: its rational part in delirium and sleep, and all three components – especially the spirited soul – in the different forms of fainting.

In terms of interaction between body and soul (and the instrumentalist versus materialist debate), our authors’ understanding of impaired consciousness suggests that all these medical models of the soul had a strong functional component. From the Hippocratic texts onwards we can see that their grasp of diseases where consciousness was impaired is based on the compromise of certain capacities (or the abolition of all of them in cases of fainting), and that medical debates focused on which those capacities were, how they were grouped (or subsumed into larger constructs) and where exactly in the body they were located.

From a chronological point of view one can see a progressive identification and isolation of such functions, particularly after the anatomical Hellenistic developments, where perceptions and movement started to play a more central role in most explanations, thereby reducing the relevance of more vague Hippocratic concepts, such as sunesis, phronêsis, nous. Simultaneously, the idea of a ruling part also reduced the debates on locations to the cardiocentric versus the encephalocentric stance. Notwithstanding all these simplifications, the tension between body and soul remained unchanged, in the sense that conditions like delirium, sleep and leipothumiê tended to be regarded as diseases where the soul (or its rational part) was primarily affected and, through it, the body (in other words, an instrumentalist stance), whereas sunkopê was mainly conceived as a bodily condition that interrupted several capacities that belonged to or depended on the integrity of the soul (the materialistic view). Of course, it is our current understanding of consciousness as a continuum and of syncopes as a form of swoon that allows us to understand this distinction as artificial.