Throughout the ages, dreaming has served as an analogy for the creation of literary fictions to such an extent that this analogy has turned into a metaphorical commonplace, evoked whenever we nonchalantly refer to Hollywood as a dream factory or to our nocturnal dreams as a dream theatre. Depending on cultural context and individual inclination, the metaphor of fiction as dream has been either negatively or positively connoted, ranging from a view of dreams as meaningless fancies to a view of dreams as divine revelations. Countless writers have, moreover, embraced the notion of a ‘dream-and-literature-symbiosis’,¹ claiming to find creative inspiration and sustenance in their dreams, while their experiences have in turn inspired philosophical reflections. Thus, the Italian Renaissance philosopher Girolamo Cardano (1501–1576) viewed dreaming and artistic creation as analogous processes, showing ‘an awareness that dream and art function as modes capable of extending the imagination’s creative powers’.² Paracelsus (1493–1541), too, acknowledged the dream’s creative potential and its inspirational value for artists: ‘Frome time immemorial artistic insights have been revealed to artists in their sleep and in dreams, so that at all times they ardently desired them’.³ With the rise of Romanticism the aesthetic quality of the dream itself was increasingly emphasized,⁴ culminating in Samuel Taylor Coleridge’s (1772–1834) view of poetry as a ‘rationalized dream’⁵ and Jean Paul’s (1763–1825) notion of dreaming as ‘involuntary poetry’.⁶ Even Robert Macnish (1802–1837), a nineteenth-century philosopher firmly rooted in the materialist tradition, marvelled that the imagination could produce dreams ‘lighted up with Prothean fire of genius and romance; […] magnificent poetry; [and] peopled with new and unheard-of imagery’.⁷ These ideas still reverberate in present times, for instance in Jorge Luis Borges’ (1899–1986) rephrasing of Coleridge and Jean Paul respectively in his references to literature as a ‘directed dream’ and to the act of dreaming as ‘perhaps the most ancient aesthetic expression’.⁸

In Such Stuff as Dreams: The Psychology of Fiction (2011), Keith Oatley takes his cue from such analogies, in particular drawing on William Shakespeare’s concept of the dream as a ‘model world’⁹ from which the Bard’s ‘idea of theater as model-of-the-world’,¹⁰ comparable to a dream, could develop. In his stimulating study on the psychology of fiction, Oatley repeatedly refers to this dream analogy:

‘Dream’ is a good metaphor for fiction because most of us have experience of dreaming and know that dreams are somewhat apart from the ordinary world. We know, too, that they are constructed by ourselves. They are not direct impressions of the world, and they may be meaningful.¹¹

Content with metaphorical evocations of the dream, however, Oatley stops short of posing the question that almost inevitably suggests itself: If dreams and fictions are so intimately connected, might not the ‘psychology of fiction’ be the same as, or at least closely related to, the psychology of dreaming? And, if so, might not his study of ‘what happens psychologically when we engage with fiction as readers or audience members, and of what we are doing as writers and performers’,¹² infinitely profit from taking into account the findings of contemporary sleep and dream research? After all, both dreaming and waking fictions can be considered as manifestations of the same ‘literary mind’,¹³ to use Mark Turner’s much-cited phrase, and the vast majority of dream researchers today emphasize the creative, expressive and imaginative qualities of dreams.

Dreams figure prominently in literary writing,¹⁴ which is hardly surprising given that dreaming is a cross-cultural universal activity.¹⁵ After all, we spend one third of our lives in sleep, and research has shown that during that seemingly passive and restive state, we dream in regular cycles, several times a night, regardless of whether we recollect our dreams or not.¹⁶ Even though more than 95 % of our dreams may go unremembered,¹⁷ those remaining 5 % give evidence of a private and fascinating world of our own, a world that defies natural laws and is all the same experienced as real while the dream lasts. As Lord Byron aptly writes: ‘…Sleep hath its own world,/And a wide realm of wild reality’.¹⁸ This world is not bound to time and space and can carry us back and forth between distant childhood scenarios and the previous day, taking us in one instant to our present workplace (curiously refashioned) and in the next to a classroom 30 years ago (curiously resembling our present workplace). The next moment, we find ourselves trapped in some hijacked plane, a house under siege, stuck in the middle of a traffic jam or walking on a beautiful Southern beach. Our dreams can be variously populated by people we know or used to know, by people we have never before encountered (though they may bear vaguely familiar traits) or by odd composites. Sometimes, these dream characters undergo transformations before our very eyes, from stranger to friend or from baby to bird. In dreams, we tend to take such transformations in our stride, unblinkingly accepting for real the most outlandish occurrences, such as being chased by humanoid monsters or visited by long-dead relatives. At times we can accomplish things we never could in waking life, like flying unaided; we can live through dramatic situations and intricate plots ranging from the everyday to the extraordinary; and we can experience the entire spectrum of emotions, from overwhelming elation to profound embarrassment to mortal fear. While it lasts, the dream is the only reality we know,¹⁹ but it is a reality that can never be shared at first hand and that tends to evaporate or haphazardly survives in fragmentary glimpses or clumsy dream reports that never quite capture the actual dream experience. Upon waking, the bits and pieces recollected from our dreams often appear bizarre, nonsensical or simply mundane. At other times, they seem to provide spiritual guidance, insights into the hidden depths of our psyches or even prophetic glimpses of the future. On notable occasions, dreams have been known to trigger scientific discoveries, groundbreaking problem-solving as well as aesthetic creations.²⁰ Finally, dreams can feel ‘real’ enough to blur the boundaries between waking and sleeping, sanity and madness, truth and delusion, thereby providing a rich source of inspiration for artists and philosophers alike.

The dream, then, is a powerful, if elusive, second reality that has inevitably invited speculation about its origins, functions and meanings. As Cavallero and Foulkes put it: ‘Dreaming is, after all, a manifestation of the human mind, and perhaps the one that has most tantalized and puzzled us throughout our recorded history’.²¹ According to William Dement, ‘the emotional impact of our dreams can be so powerful that they might as well have occurred’, which is one reason why dreams have ‘fascinated people since at least the beginning of recorded history’.²² Attempts to explain the phenomenon of dreaming have ranged from a belief in supernatural visitations and spiritual night journeys on one end of the spectrum to naturalized (somatic, psychological, psychoanalytical or neurocognitive) models on the other. In Gover and Khan’s words:

Dreams have alternately been hailed as messages from the gods and dismissed as random hallucinations. The pendulum of popular opinion has swung from one extreme to the other throughout recorded history and between cultures and camps, with scientists, psychologists, sages, and philosophers all weighing in.²³

Between the two extremes, however, a great diversity of attitudes to dreams in terms of their origins, functions and value can be detected.

In Homeric times, for instance, dreams were not considered as subjectively generated internal experience, but rather as objectified messengers sent by a deity or by the dead. Their value was determined by their prophetic accuracy and whether they had come through the gates of horn or through the gates of ivory. As Penelope explains to Odysseus:

For there are two gates of insubstantial dreams; one [pair] is wrought of horn and one of ivory. Of these, [the dreams] which come through [the gate of] sawn ivory are dangerous to believe, for they bring messages which will not issue in deeds; but [the dreams] which come forth through [the gate of] polished horn, these have power in reality, whenever any mortal sees them.²⁴

While the Homeric conception of dreams implied that the sleeper was visited by a dream, in later classical antiquity, this idea was expanded, in that the soul was now believed to leave the body and travel to the spatially envisioned dream world, where it ‘could wander at will, free from earthly shackles’.²⁵ With the emergence of the Judeo-Christian tradition, the concept of true versus false dreams was complicated by the notion of good versus evil dreams. As Parman points out: ‘The divine itself was bifurcated into good and evil. Angels and devils populated the eternal realm, fighting for the occult soul. Dreams were still a bridge to the supernatural, but dreamers were encouraged to distrust their dreams, not knowing if they were sent by angels or devils’.²⁶

Such supernatural dream beliefs were rivalled by naturalistic ones. Rather than endorsing the Homeric view that dreams are messages from the Gods, Aristotle, for instance, viewed them as ‘images produced by interconnecting phys...