Theory

Freud didn't exactly invent the idea of the conscious versus unconscious mind, but he certainly was responsible for making it popular. The conscious mind is what you are aware of at any particular moment, your present perceptions, memories, thoughts, fantasies, feelings, what have you. Working closely with the conscious mind is what Freud called the preconscious, what we might today call "available memory:" anything that can easily be made conscious, the memories you are not at the moment thinking about but can readily bring to mind. Freud suggested that these are the smallest parts!
The largest part by far is the unconscious. It includes all the things that are not easily available to awareness, including many things that have their origins there, such as our drives or instincts, and things that are put there because we can't bear to look at them, such as the memories and emotions associated with trauma.

According to Freud, the unconscious is the source of our motivations, whether they are simple desires for food or sex, neurotic compulsions, or the motives of an artist or scientist. And yet, we are often driven to deny or resist becoming conscious of these motives, and they are often available to us only in disguised form. We will come back to this.

The Libido, or Psychic Energy, in Freud
David B. Stevenson '96, Brown University Freud conceived of the mind as having only a fixed amount of psychic energy, or libido. Though the word libido has since acquired overt sexual implications, in Freud's theory it stood for all psychic energy. This energy fueled the thought processes, perception, imagination, memory, and sexual urges. In Freud's theory, the mind, like the universe, could neither create nor destroy energy, but merely transfer it from one form or function to another. Because scope of the mind's capabilities was thus limited by