Dreams, arguably, are one of the biggest mysteries of humankind. For centuries people have been fascinated by our extraordinary ability to experience things, at times almost corporeally, in a state of sleep. This mystery has produced hundreds of possible explanations of why we dream, what our dreams mean, and how they come to be—from beliefs and superstitions of ancient Egyptians to the latest discoveries of neuroscience. In the modern world, many might be inclined to think that the innovative scientific conclusions are the ultimate truth; however, as far as history is concerned, it is very likely that a couple of centuries from now our current science-based convictions regarding the nature of dreams will be seen as ideas just as far-fetched and archaic as those of the ancient Romans seem to us.

Alchemy was once regarded as the most advanced branch of Mediaeval science—and now it belongs in history books and museums. That being the case, I believe that turning one’s gaze to the tenets of our ancestors is a curious and useful practice that puts things marvellously into perspective, reminding us of the fleeting nature and inescapable relativity of every point of view, however reasonable and grounded in research it might seem at the time. With that being said, let us take a step back from modern science and look at how ancient religions and civilizations approached the eternal mystery of dreaming.

Ancient Egypt

Although sources that shed light upon how ancient Egyptians viewed the process of dreaming are quite limited—not only because archaeological sources of that period are in general relatively scarce, but also because ancient Egyptians, apparently, were not very keen on recording their dreams—the British Museum’s “Dream Book,” preserved on papyrus, provides interesting insights into the topic. Curiously, ancient Egypt did not have a verb for dreaming—only a noun, resut, which paradoxically literally translates to “awakening.” This means that dreaming was not an action, rather an object of visual perception, an independent happening which a sleeping person can observe without necessarily taking part in it. Dreams were thus believed to have an objective existence outside of the sleeping mind and were often regarded as places of contact between the worlds.

Ancient Greece

Ancient Greeks regarded dreams first and foremost as messages or prophecies coming directly from spirits, gods or other supernatural beings related to the Greek pantheon. Perhaps the most famous deity whose power is connected to dreams is Morpheus, God of dreams, often referenced in Romantic poetry with notable examples of Samuel Taylor Coleridge and John Keats. In Greek myths, various gods can often be caught sending dreams to the mortals in order to warn them of the imminent danger or prompt them to certain action; a similar tendency can be found in classic Greek literature. For example, in Aeschylus’s classic tragedy Oresteia Clytemnestra dreams of giving birth to a serpent, which foreshadows her subsequent death from the hands of her own son, Orestes, who was ordered to kill her by Appollo as revenge for her murder of Orestes’ father.

Ancient Rome

Similarly to ancient Greece, ancient Rome had a tradition of interpreting dreams as omens, prophecies, or divine guidance. Dream interpretation per se was a respected practice, with even the wisest men of the era reflecting on the topic in their writing – for example, Cicero, who discusses dreams as a form of divination in his De Divinatione. Although often retaining a rather skeptical attitude, Cicero offers his readers multiple examples of dreams foreshadowing events, be it military victories or personal fates, ultimately questioning: “For what is that which bursts forth from the soul during sleep, such that the future seems to be revealed?” (Book 1, Section 30).

Hinduism

Hindu notions of dreams were closely tied to ancient texts such as Puranas, Vedas, and Upanishads. In the Mandukya Upanishad, for instance, dreaming (swapna) is listed as one of the four states of consciousness alongside waking (jagrath), deep sleep (sushupthi), and a transcendent fourth state (turiya). As such, dreams were perceived either as experiences where the soul temporarily leaves the body or as expressions of a person’s hidden desires. Based on sacred Hindu texts, Boban Eranimos and Dr. Art Funkhouser offer a classification of dreams with seven distinct types of dreaming:

  • Dreams reflecting past experiences.

  • Dreams indicating future events.

  • Dreams caused by disturbances in the body.

  • Dreams resulting from divine messages.

  • Dreams influenced by one’s mental state.

  • Dreams arising from the imbalance of bodily humors.

  • Dreams that are meaningless or inconsequential.

In contrast to the three aforementioned approaches, the Hindu views on dreaming seem to incorporate the body significantly more into the question, and equally ground dreams in corporeal as well as in divine.

Buddhism

Dreams in Buddhism serve mainly as a lens to better understand the mind and deepen one’s spiritual practice: they help cultivate awareness and liberate the mind from illusions. In some branches of Buddhism, dreams also play an important role in the path to enlightenment—experienced by advanced practitioners, they become spiritual messages or visions on the way to bodhi. Siddhartha Gautama, for one, is believed to have had many dreams right before his enlightenment, including the famous dream of a white elephant entering his mother’s womb, which symbolized his (re)birth as a Bodhisattva. However, the most common approach is to regard dreams either as mere manifestations of mental activity, arising from habitual patterns of the mind and reflecting current mental states, or as symbolic opportunities for self-reflection or spiritual growth.

Judaism

In Judaism, dreams (chalomot) are viewed as a medium through which God or the subconscious may communicate with a person. A classic example of that can be found in Genesis: Joseph, sold into slavery in Egypt by his envious younger brothers, successfully deciphers Pharaoh’s dreams—seven sleek and fat cows being eaten by seven ugly and gaunt ones, and seven full and healthy heads of grain being swallowed by seven thin and withering ones (Genesis 41). Joseph interprets these visions as a prediction of seven years of prosperity followed by seven years of famine and thus saves Egypt from misery. The Talmud, however, teaches that dreams are “one-sixtieth of prophecy” (Berakhot 57b), meaning not only that dreams are only one part truth and five parts illusion, but also that a skilled interpretation of a dream’s symbolism plays a key role in understanding its prophetic meaning.

Islam

Islam views dreams as a mix of spiritual messages, psychological processes, and external influences, and categorizes them accordingly into three types. First one, divine dreams (ru'ya saliha), are those that contain messages or guidance from Allah and can often be read as blessings or warnings. The second, satanic dreams (hulm), are dreams sent by Shaytan to cause fear or distress. Finally, the third type, self-reflective dreams (nafs), are results of one’s own experiences, thoughts and desires. Similar to other religions, Islam considered dream interpretations a useful and respected practice, with figures like Prophet Yusuf (Joseph) playing an important role in the Qur’an.

The more modern ideas on dreams stand, naturally, in strong opposition to the religion-driven beliefs described above. Starting with Freud, many theories sprung up in the past two centuries that explain the nature and mechanisms of dreaming. A few notable examples would be:

  • Psychoanalytic theory (Sigmund Freud) that suggests that the traumas and desires of our subconscious mind are “encoded” in our dreams,

  • Consolidation of memories theory (Matthew Wilson, Robert Stickgold) that implies that the brain uses dreams to reorganize data, sending newly acquired skills into long-term memory and unsolved problems are into short-term one, and the opposite reverse learning theory (Francis Crick and Graeme Mitchison) which proposes that dreams are a side-effect of the brain discarding (or “unlearning”) unnecessary information in order to increase its performance in the waking state,

  • Activation-synthesis hypothesis (J. Allan Hobson and Robert McCarley) which points out that since inactivity of visual cortex during sleep leads to its gradual decline, the brain generates random images – dreams – to keep the cortex stimulated,

  • Problem-solving theory (Rosalind Cartwright) which indicates that the sleeping brain is less subject to the laws of habitual logic and can therefore offer atypical solutions to the problems of our waking mind,

  • Emotional regulation theory (Rosalind Cartwright, Erin Wamsley and Jessica Payne) suggests that we dream to process and heal from emotional experiences, since (re)living traumatic events in dreams can help reduce their impact in waking life.

After all, it is impossible to say which religion or theory is correct, and the truth, as is often the case in such debates, likely lies somewhere in between. Perhaps in a few centuries from now new discoveries will shed unprecedented light on the topic and bring it to it’s ultimate conclusion; but in my personal opinion it is far more likely that in the future, same as in our time and in all the times before us, everyone will have to decide for themselves which one of the millions of answers to life’s thousands of questions they want to adopt – the question of “why do we dream?” included.