in 1895 Sigmund Freud started work on The Interpretation of Dreams. In a letter in 1900 he wrote:
“Do you suppose that some day a marble tablet will be placed on the house, inscribed with these words: ‘In this house on July 24, 1895, the secret of dreams was revealed to Dr. Sigm. Freud’? At the moment I see little prospect of it.”
This video outlines Freud’s theory of why we dream along with some others from neuroscientific study.