In the 1890's, psychotherapist Frederik van Eeden began a study of his own dreams by keeping a journal that allowed him to categorize the kind of dreams that he was having. In an attempt to classify the different forms of dreams that he experienced and observed for a period of 16 years or more, he documented nine different kinds of dreams. His paper entitled "A Study of Dreams" was published in 1913 in Proceedings of the Society for Psychical Research and remains a classic of dream research. Eeden is credited for having coined the phrase "lucid dream".