From approximately 1550 BCE to the 18th century, numerous people speculated on the intricacies of the mind and its working, including Pythagoras, Socrates, Hippocrates, Aristotle, Aulus Cornelius Celsus, Rene Descartes and John Locke. The contemporary foundations of psychology began in 1879 when the first psychology laboratory was created by Wilhelm Wundt in Leipzig, Germany. Important figures include Jean Piaget, Sigmund Freud, Carl Jung, Carl Rogers and Paul Broca.
When Aulus Cornelius Celsus died, he left behind a medical encyclopedia, within which the third book was of mental diseases. Celsus was the first to use the term insanity and to suggest music therapy, massage, sport, travel and reading aloud. In 705 CE, the first psychiatric hospital was created in Baghdad. Rudolph Goclenius coined the term psychology in 1590. In 1808 the term psychiatry was coined by Johann Christian Reil. After studying under Wundt at his laboratory in Leipzig, G. Stanley Hall moved to the United States to open the first experimental psychology research laboratory in 1883 at Johns Hopkins University. In 1884 Ivan Pavlov began studying the digestive secretions of animals, which resulted in his famous classical conditioning experiment involving a salivating dog. In 1886 Sigmund Freud started his private practice located in Vienna. The American Journal of Psychology was founded by G. Stanley Hall in 1887, and since then, it has published numerous papers in the field. Hall later went on to establish the American Psychological Association in 1892. In 1910 the International Psychoanalytical Association was founded by Sigmund Freud, and Carl Jung was the first president.