In this passage from The Use of Poetry and the Use of Criticism (public library), cited in the 1942 gem Anatomy of Inspiration, celebrated poet, playwright, and cultural critic T. S. Eliot adds to previously explored theories of how creativity works by taking a curious look at how physical illness brings a near-mystical quality of poetry, driven by two key elements of creativity: the presence of an incubation period when unconscious processing of existing ideas takes place, and the removal of habitual inhibitions, or something John Keats has termed “negative capability”.

That there is an analogy between mystical experience and some of the ways in which poetry is written I do not deny … though, as I have said, whether the analogy is of significance for the student of religion or only to the psychologist, I do not know. I know, for instance, that some forms of ill-health, debility or anaemia, may (if other circumstances are favourable) produce an efflux of poetry in a way approaching the condition of automatic writing — though, in contrast to the claims sometimes made for the latter, the material has obviously been incubating within the poet, and cannot be suspected of being a present form a friendly or impertinent demon. What one writes in this way may succeed in standing the examination of a more normal state of mind; it gives me the impression, as I have said, of having undergone a long incubation, though we do not know until the shell breaks what kind of egg we have been sitting on. To me it seems that at these moments, which are characterised by the sudden lifting of the burden of anxiety and fear which presses upon our daily life so steadily that we are unaware of it, what happens is something negative: that is to say, not ‘inspiration’ as we commonly think of it, but the breaking down of strong habitual barriers — which tend to re-form very quickly. Some obstruction is momentarily whisked away. The accompanying feeling is less like what we know as positive pleasure, than a sudden relief from an intolerable burden. … This disturbance of our quotidian character which results in an incantation, an outburst of words which we hardly recognise as our own (because of the effortlessness), is a very different thing from mystical illumination. The latter is a vision which may be accompanied by the realisation that you will never be able to communicate it to anyone else, or even by the realisation that when it is past you will not be able to recall it to yourself; the former is not a vision but a motion terminating in an arrangement of words on paper.