Religious and mystical experiences have profound meanings for the lives of people across all cultures. William James, a lecturer in anatomy and physiology at Harvard in the late 19th century, approaches these experiences with an empirical eye, at a time when psychology was beginning to diverge from philosophy. He takes great interest in dissecting the subjective experiences of individuals, drawing upon autobiographies and other first-person accounts of encounters with the divine and in doing so wrote a seminal text about the psychology and psychiatry of religious experiences.

In his book The Varieties of Religious Experiences are found many passages of first-person accounts that contain elements of hallucinations, passivity phenomena, delusional moods and possibly aberrant salience. James acknowledges that he draws upon ‘the mass of collateral phenomena, morbid or healthy’ to better understand religious phenomena. He maps out these experiences from which he strictly excludes shared experiences through communities, institutions or religious dogma, including only the solitary experiences of individuals. His accounts vary from the mundane to the extreme, distilling from them the characteristics of religious and mystical experiences: ineffability, noetic quality, transiency and passivity.

There are numerous first-person accounts, including the following illustrative excerpts. On the common end of the spectrum: ‘When I walk the fields, I am oppressed now and then with a feeling that everything I see has a meaning, if I could but understand it. And this feeling of being surrounded with truths which I cannot grasp amounts to indescribable awe sometimes …’ On the more extreme end: ‘… whilst resting in the afternoon, I suddenly heard as it were these words: “You will be healed and do a work you never dreamed of.” These words were impressed upon my mind with such power I said at once that only God could have put them there.’ And the more disturbing: ‘the word of the Lord came to me again, saying: Cry, “Wo to the bloody city of Lichfield!” So I went up and down the streets, crying with a loud voice, Wo to the bloody city of Lichfield!’

James' medical peers labelled some of these religious persona as epileptics, hysterics and ‘hereditary degenerates’. James, however, ardently opposes the view that religious experiences are pathological. He writes, ‘The overcoming of all the usual barriers between the individual and the Absolute is the great mystic achievement.’ Individuals who have these experiences are religious geniuses, and these experiences are universal. He nevertheless acknowledges that there is a ‘diabolical mysticism, a sort of religious mysticism turned upside down … The same sense of ineffable importance … voices and visions … the same controlling by extraneous powers; only this time the emotion is pessimistic’.

James is in fact on a secondary mission to examine the common mechanisms between the pathological and religious experiences, to understand the merits of the latter. In doing so, he could be describing an early prototype of the psychosis spectrum. This perspective is shared across different cultures: for example, there is the Hindu Vedantists’ belief in a mystical consciousness where ‘There is no feeling of I, and yet the mind works, desireless, free from restlessness …’, one which some people may stumble into in a way which is impure. To ascertain its purity, the Vedantists looked to the results: whether this experience has changed the individual's life for the better. Across continents and cultures the same argument is echoed by Saint Teresa in her rebuttal against critics: her visions are not pathological, because they have enriched her life and bestowed her with her virtues. There seems to be a way to differentiate between beneficial and maleficent religious experiences; James would argue that this is by looking at their outcomes.

James' investigation of religious and mystical experiences, which explore psychotic experiences as collateral, can inspire the modern psychiatrist not only in its impressive synthesis of varied and rich experiences – a much needed undertaking at a time when the concept of schizophrenia is being deconstructed – but also in its philosophical stance of pragmatism: rather than focusing on the origin of the experience of belief, whether that be through reductive diagnostic criteria, genetics or neurophysiology, focusing instead on the ‘way in which it works on the whole’ – the impact that the experiences have on the individual. I would like to think that if James were alive today, he would be reaching across disciplines, deconstructing the concept of schizophrenia by way of phenomenology and epidemiology.