Before we turn to the really big names, let's take a peek at the concept of the unconscious, so strongly associated with psychoanalysis. Most historians agree that the first mention of such a concept was Leibniz's discussion of "petites perceptions" or little perceptions. By this he meant certain very low-level stimuli that could enter the mind without the person's awareness - what today we would call subliminal messages. The reality of such things is very much in doubt.

Johann Friedrich Herbart (1776-1841) was the author of a textbook on psychology, published in 1816. But, following Kant, he did not believe psychology could ever be a science. He took the concepts of the associationists and blended them with the dynamics of Leibniz's monads. Ideas had an energy of their own, he said, and could actually force themselves on the person's conscious mind by exceeding a certain threshold. When ideas were incompatible, one or the other would be repressed, he said - meaning forced below the threshold into the unconscious. This should remind you of Freud's ideas - except that Herbart had them nearly a century earlier!

Schopenhauer is often seen as the originator of the unconscious, and he spoke at great lengths about instincts and the irrational nature of man, and freely made use of words like repression, resistance, and sublimation! Nietzsche also spoke of the unconscious: One of his most famous statements is "My memory says I did it. My pride says I could not have done that. In the end, my memory yields."

One more pre-Freudian should be mentioned:  Karl Eduard von Hartmann (1842-1906).  He blended the ideas of Schopenhauer with Jewish mysticism (the kaballah) and wrote Philosophy of the Unconscious in 1869, just in time to influence a young neurologist named Sigmund Freud.

The reader should understand that there are many theorists with little or no use for the concept of the unconscious.  Brentano, forefather of phenomenology and existentialism, did not believe in it.  Neither did William James.  Neither did the Gestalt psychologists.  Memories, for example, can be understood as stored in some physical state, perhaps as traces in the brain.  When activated, we remember.  But they aren't in the mind - conscious or unconscious - until so activated.

In addition to the concept of the unconscious, another early landmark of psychiatry was the introduction of careful diagnosis of mental illness, beginning with Emil Kraepelin's work (1856-1926).  The first differentiated classification was of what he labelled dementia praecox, which meant the insanity of adolescence.  Kraepelin also invented the terms neurosis and psychosis, and named Alzheimer's disease after Alois Alzheimer, who first described it.  I should also mention Eugen Bleuler, who coined the term schizophrenia to replace dementia praecox in 1911.

Now, on to Freud....