Stephen Prickett (1939–2020) argued that concepts of our Secret Selves – our identity, individuality, imagination, consciousness and unconsciousness – our ‘infinite inner space’ – evolved over the centuries, shaped by changing external contexts. Long ago, our ancestors did not distinguish real and hallucinatory sensory inputs. In some eras, people explained dreams as external, supernatural or divinely inspired. Dreams have been used as vehicles of comedy and literary devices, as in Shakespeare's A Midsummer Night's Dream, Dickens's A Christmas Carol and Carroll's Alice books. They may also have inspired great artists: Hieronymus Bosch painted heaven and hell and, unusual for the 1500s, depicted hell as contemporary warfare, destruction and desolation created by humans.

As well as creations derived from our ‘inner space’, Prickett explored the etymology of pertinent words. ‘Identity’ has a ‘tortuous lexical history’, he wrote, from the Latin idem, meaning ‘the same’. It could mean a person being the same over time, or being the same as others, but by the mid-17th century, it came to mean ‘individuality’ or ‘personality’, i.e. difference rather than sameness. Nevertheless, it is still used collectively: an ‘identity card’ indicates group membership, often citizenship.

Many aspects of mind in Prickett's book were new to me, and fascinating, but it was hardly an easy read. Perhaps I should not have been surprised, given that the author was a Professor of English and the dust jacket critiques were by experts in English and Christianity. To understand the book thoroughly demands greater preliminary understanding of those subjects than I have. To appreciate how Dante's heaven, purgatory and hell in The Divine Comedy relate to Freud's superego, ego and id requires some knowledge of Christianity, literature and psychoanalysis, before reading Prickett's work.

The book covers a vast terrain of European Christian culture, but I was left feeling that the story was incomplete owing to the lack of other cultural and religious dimensions. The contents did not match the breadth implied by the title. Even when discussing ‘double consciousness’, an awareness of ourselves as individuals at the same time as seeing ourselves ‘as if we were external spectators of our own actions’, he used the example of lecturing to a public audience, rather than explaining that the term was derived from fin de siècle racialised oppression and social devaluation of African Americans in a White-dominated society.

Understanding of our individuality keeps shifting, and Prickett speculated on what the future might bring. One day we might all be cyborgs with cyberidentities and electronic brain implants. What would identity theft mean then? Might our inner space be hacked? How might we need to reconceptualise our inner selves? Whether Dante's and Freud's concepts are passé, remain the same or are remodelled, history suggests that some fantasies derived from our secret selves may come to fruition.