Dreams have been reflected and interpreted by human beings from very ancient times and have remained a mystery most of the time. Dreams have puzzled human beings from ancient times. Sometimes they were looked upon as devilish forces and sometimes as a message from God. Heraclitus had the view that the soul has contact with the cosmic region (logos) when it is free from the interruption of the senses, that is in the state of being asleep. According to Homer, dreams come from the underworld of Hades (the Greek purgatory), and sleep (Hypnos) and death (Thanatos) are twin brothers (The Iliad, xvi). Freudian work is well-known in the psychological field.

For Freud, dreams are the royal road of our unconscious mind. He describes the unconscious as a representation of all the repressed desires and impulses, which are mostly sexual in nature. Jung added the concept of the racial unconscious in dreams. Dreams also convey the memories of our ancestral past and experiences of human beings from the very beginning of human life. There is a vast literature on dreams which includes the psychological and the physiological aspects of dreams. Dreams can be creative and problem-solving. A few examples of dream-inspired work and the resulting phenomenal success include-

- The Nobel Prize-winning work of Otto Leowi.
- Ellis Howeís discovery of the sewing machine.

These dreams are discussed in detail in Chapter 4 of this book where famous historical dreams have been presented. Islamic view on dreams recognizes that dreams are based on past experiences, feelings of the dreamer, wish fulfilment in the dream, etc. It also gives full recognition to true dreams, which can also be called predictive dreams, and serves the purpose of giving glad tidings or warnings to the dreamer based on specific scenarios. The Islamic views on dreams have been elaborately discussed because they are rarely organized particularly in the English language.