The Stoic roots of cognitive behavioural therapy A possible explanation for the early link between philosophy and psychotherapy was proposed towards the end of the twentieth century by French philosopher and classicist Pierre Hadot (1922–2010) [54]. According to Hadot, ancient discourse on logic, physics, and ethics was ultimately aimed at the practical goal of changing people’s lives. Starting from the Socratic schools, the aim of philosophy as a way of life was to ‘transform’ rather than to ‘inform’ students. Practical philosophy inaugurated a tradition of ‘spiritual gymnastics’, in Hadot’s words. Following the Renaissance and the revival of classical studies, a range of ‘spiritual exercises’ were codified in a set of religious meditations, contemplations, and prayers in the sixteenth century by Ignatius of Loyola. With the return of secularism, the role of the practical philosopher of antiquity has been revived as a guide to modern living. Specifically, analysis of the texts of the Roman Stoics suggests that different types of psychotherapy currently in use can be traced back to the Stoic tradition of philosophical therapy [61–65]. Stoicism was explicitly credited as the philosophical foundation of cognitive behavioural therapy [66, 67]. Albert Ellis, the founder of rational emotive behaviour therapy, referred to Epictetus as ‘a remarkably wise Stoic [who] pointed out some of two thousand years ago that you choose to overreact to the obnoxious behavior of others while you could more wisely choose to react in a very different manner’ [68]. Admittedly, the basis of his therapeutic approach ‘was originally discovered and stated by the ancient Stoic philosophers, especially Zeno of Citium (the founder of the school), Chrysippus (his most influential disciple), Panaetius of Rhodes (who introduced Stoicism into Rome), Cicero, Seneca, Epictetus, and Marcus Aurelius. The truths of Stoicism were perhaps best set forth by Epictetus, who, in the first century AD wrote in the Enchiridion: ‘Men are disturbed not by things, but by the views which they take of them’. Shakespeare, many centuries later, rephrased this thought in Hamlet: ‘There’s nothing good or bad but thinking makes it so’’ [69]. Despite the chronological inaccuracy (Epictetus’ words were actually written down in the ‘Εγχειρίδιον’ — literally, ‘Handbook’ — by his disciple Arrian in the first half of the second century), Ellis’ statement clearly shows that he was fully aware of his debt to his illustrious predecessor. The key difference between the ‘second wave’ of cognitive behavioural therapies and behaviourism is a crucial point: emotional disturbances and neuropsychiatric symptoms are not due to external events, but to our irrational beliefs about such events. In his first major publication on rational emotive behaviour therapy, Ellis stressed that the central premise of the emerging cognitive approach to psychotherapy could be traced back to the ancient Stoics: ‘By direct statement and implication, then, modern thinkers are tending to recognize the fact that logic and reason can, and in a sense must, play a most important role in overcoming human neurosis’. Eventually, they may be able to catch up with Epictetus in this respect, who wrote — some nineteen centuries ago — that ‘the chief concern of a wise and good man is his own reason’ [69]. A few years later, Ellis proudly claimed to have single-handedly rescued Epictetus from oblivion: ‘I am happy to say that in the 1950s I managed to bring Epictetus out of near-obscurity and make him famous all over again’ [70]. Such a bold statement might sound like an exaggeration; however, it was mainly through Ellis’ writings that Stoicism exerted its influence on Aaron Beck, the father of second-wave cognitive behavioural therapy. Beck opened his first book on cognitive therapy by acknowledging the foundations of the concept that cognitions play a central role in determining our emotions: ‘the philosophical underpinnings go back thousands of years, certainly to the time of the Stoics, who considered man’s conceptions (or misconceptions) of events rather than the events themselves as the key to his emotional upsets’ [71]. While describing his cognitive therapy approach, Beck quoted Baruch Spinoza (1631–1677) alongside the ancient Stoics: ‘I saw that all the things I feared, and which feared me had nothing good or bad in them save insofar as the mind was affected by them’ [71]. Apparently, the echoes of Epictetus’ words had not ceased to resonate in the words of some of the most influential thinkers of all times. Michel de Montaigne (1533–1592) took a somewhat more pragmatic approach, as he famously had Epictetus’ mantra among the Greek and Latin sentences carved into the beams of the rafters of his library (Fig. 1). Fig. 1. Open in a new tab Epictetus’ words ‘ταράσσει τοὺς ἀνθρώπους οὐ τὰ πράγματα, ἀλλὰ τὰ περὶ τῶν πραγμάτων δόγματα’ (‘men are disturbed not by things, but by the views which they take of things’) in a carved beam from Michel de Montaigne’s library (Château de Montaigne, France)Of note, a contemporary of Montaigne, the humanist Justus Lipsius (1547–1606), revived ancient Stoicism by establishing Neostoicism as a widespread philosophical current of thought at the end of the Renaissance [72]. Lipsius famously justified the use of pagan philosophy (‘bonae litterae’) in place of the holy texts (‘sacrae litterae’). Based on his reading of the Roman Stoics, he developed a model of practical philosophy that is guided by reason and is immediately applicable to daily life. These ideas quickly spread and were endorsed by Guillaume Du Vair (1556–1621), the leading exponent of Neostoicism in late sixteenth century France. Long-reaching influences involved psychotherapy: between the end of the nineteenth century and the beginning of the twentieth century, the practice of a few French-speaking psychotherapists was explicitly informed by Stoicism [73]. In particular, the Swiss neurologist and psychotherapist Paul Dubois (1829–1905) founded a ‘rational persuasion’ approach to psychotherapy, which is largely forgotten today but which prefigured modern cognitive behavioural therapy in many respects [74]. However, it is with the work of English-speaking psychotherapists that Roman Stoicism was fully brought to light again as the foundation of cutting-edge treatment interventions in the Western world. In 1979, Beck and his colleagues sealed the concept that the doctrines of Stoicism constitute the philosophical origins of cognitive therapy in their groundbreaking treatment manual for clinical depression: ‘The philosophical origins of cognitive therapy can be traced back to the Stoic philosophers, particularly Zeno of Citium (fourth century BC), Chrysippus, Cicero, Seneca, Epictetus, and Marcus Aurelius. Epictetus wrote in The Enchiridion: ‘Men are disturbed not by things but by the views which they take of them’ […] Control of most intense feelings may be achieved by changing one’s ideas’ [75]. According to the most influential authors, the cognitive revolution might have taken place two thousand years before what is commonly held.Stoic exercises and mindfulness practice The third wave of cognitive behavioural therapies is represented by a growing list of evidence-based treatment strategies [9]. Among these interventions, mindfulness-based therapy has gained momentum as a recommended intervention for a range of neuropsychiatric conditions [59, 60]. Mindfulness promotes self-awareness and concentration on the present moment, in order to achieve freedom from unhealthy emotions, which are rooted either in the past (e.g. depression) or in the future (e.g. anxiety). Although mindfulness has traditionally been linked to Eastern philosophies such as Buddhism, it is worth noting that its practice is not new to the Western tradition, as it can be traced back to the Stoic armamentarium of ‘spiritual exercises’ [76]. Specifically, the practice of mindfulness closely matches the Stoic exercise of attention (‘προσοχή’, which can be translated as ‘concentration on the present moment’ — or indeed ‘Stoic mindfulness’) [74, 77]. As a striking example of the Stoic form of mindfulness, in his ‘Meditations’ Marcus Aurelius reminded himself (and all of us) that those who fail to pay attention to their own thoughts and know their own minds are bound to be unfulfilled in life: ‘Through not observing what is in the mind of another a man has seldom been seen to be unhappy; but those who do not observe the movements of their own minds must of necessity be unhappy’ [55]. Marcus Aurelius’ ‘Meditations’ could be read as an early example of a modern therapy journal. As part of their cognitive behavioural treatment intervention, patients are often asked to keep a diary (journal) where they write down their thoughts and reflect on their behavioural patterns. The very practice of recording own thoughts and feelings was adopted by Marcus Aurelius in his Meditations, a book that was not intended for publication and is sometimes titled ‘Τὰ εἰς ἑαυτόν’ or ‘To himself’, reflecting its original purpose — an exercise of reflective practice of Stoic discipline [55]. Certain aspects of third wave approaches to cognitive behavioural therapy seem to be more in line with the Stoic conceptions of value and mindfulness, as compared to mindfulness practices derived from Buddhism, which entail greater attention to bodily states or breathing patterns [78]. Specifically, the Stoics placed considerable emphasis on the practice of focusing attention on the activity of our executive function or ‘ἡγεμονικόν’ (‘ruling faculty’). By focusing attention on the seat of our sphere of control in the present moment, it is possible to distinguish clearly between our voluntary cognition or ‘προαίρεσις’ (‘volition’ or ‘moral choice’) and our automatic thoughts or ‘φαντασίαι’ (‘involuntary impressions’). In turn, the practice of attention or Stoic mindfulness allows to take more ownership for voluntary cognition and adopting an attitude of greater detachment and indifference towards automatic thoughts, which are often the main source of distress. The concept and practice of Stoic mindfulness sheds light on rational emotive behaviour therapy as a precursor of third-wave cognitive behavioural therapy techniques, as Ellis trained his patients to closely monitor the relationship between their thoughts, actions, and feelings, whenever they presented with distressing symptoms [78]. Such emphasis on the constant attention to one’s faculty of judgment leads to increased awareness of the distinction between voluntary thoughts/actions and external events or automatic thoughts. The Stoics described this process as the separation of our thoughts and beliefs from their objects. In addition to the separation of judgments from events, the Stoics firmly asserted this principle in their ‘dichotomy of control’. In particular, Epictetus’ Enchiridion maintains a clear distinction between what is up to us (‘τὰ ἐφ’ἡμῖν’) and what is not (‘τὰ ούκ ἐφ’ἡμῖν’). What Ellis introduced to the cognitive behavioural therapy field through the saying ‘It’s not things that upset us, but our judgements about them’ is comparable to the process called ‘cognitive distancing’ in Beck’s cognitive therapy — or ‘cognitive defusion’ in third-wave acceptance and commitment therapy. There are traces of such techniques, such as talking to thoughts as if to another person to aid defusion, in Epictetus’ own practice, as he famously instructed his Stoic students to apostrophize their distressing thoughts by saying ‘You are just an impression and not at all the thing you claim to be’ [78]. There is an interesting chronological parallelism between the renewed interest in Stoicism and the development and implementation of mindfulness-based strategies into clinical practice. The original studies published by Pierre Hadot at the end of the twentieth century focused on the role of ancient philosophy as psychotherapy [54, 55]. These influential works heralded a fruitful line of research, which culminated in an unprecedented proliferation of academic publications on Stoicism since 2007 [57–59, 79–81]. It is noteworthy that in clinical sciences there has been an exponential growth of mindfulness research since 2006, with publications mainly originating from Western countries [82], and closer attention to mindfulness-based interventions since 2010 [83]. More recently, the operationalization of Stoic principles has been proposed for a number of clinical applications, ranging from genetic counselling practice [84] to interventions for stuttering [85]. In this sense, the classics can offer valuable guides for future directions. Moreover, these observations further highlight the importance of the study of classical languages and civilizations, which can help neurology rediscover its foundations, past therapeutical approaches and even ancient pathological presentations [86, 87]. The widespread implementation of Stoicism-informed psychotherapies into evidence-based clinical guidelines should not come as a surprise. Disguised by different concepts and expressed in different languages, these techniques have never ceased to accompany the journey of Western civilisation. Their persistence over time — as well as their striking similarities with principles developed within Eastern traditions — might be considered as further evidence that they carve human nature at its joints.