Id, ego and super-ego are the three parts of the psychic apparatus defined in Sigmund Freud's structural model of the psyche; they are the three theoretical constructs in terms of whose activity and interaction mental life is described. According to this model of the psyche, the id is the set of uncoordinated instinctual trends; the super-ego plays the critical and moralizing role; and the ego is the organized, realistic part that mediates between the desires of the id and the super-ego. The super-ego can stop you from doing certain things that your id may want you to do.
Funny how Freud's quaint theory was deemed so important for so long. (Is it still? I confess I don't keep up with current psychiatric theory.) Reading about it today, it seems to me like nothing but Creationism or Fairy Tales... The guy had a good imagination and a scholarly background and a fatherly/authoritative façade... And so everyone bought into what he was saying.
I think he was just trying to theorize about the trends he was seeing at the time in his own practice. There's quite a difference between trend-spotting and having some true insight. (As per much of the Bible: It was OBVIOUSLY written by guys sitting around making guesses as to the origins of the world, based solely on THEIR desert world. Dinosaurs weren't mentioned because they didn't know that they had existed. Other planets weren't mentioned because they didn't know that they existed. ET CETERA.)
I think Freud got the common-sense personality concepts of "Id" and "Ego" right. Id, the subterranean. Ego, the functional part. Totally off on the "Super-Ego" part, though. (The Ego actually performing that role.) At the time of his writing, Freud thought "the super-ego also takes on the influence of those who have stepped into the place of parents — educators, teachers, people chosen as ideal models." He meant this as a CONTROLLING force. Little understanding that, in fact, outer societal influences are often the means of PERMISSION rather than of control. At least today.
Today there's the functioning-in-the-world Ego; the at-home-alone-with-your-own-thoughts Id; and the... (sadly seemingly necessary) WILD PROJECTION AND SALESMANSHIP OF IDEAL SELF. I figured out by high school that this last "salesmanship thing" might exist. My suspicion confirmed in college and in adult work/love life. In a few wonderful instances, there's no need for such salesmanship. But, unfortunately, the majority of the time, it's required.
I think trees are so cool because of their simply DUAL nature: the outer exhibition balanced by the equally intricate workings underground. They ARE and they ARE. There's no "not really, but let's make something up and SAY it's so until it's believed as true, then congratulate ourselves for fooling others while simultaneously castigating ourselves for being so phony." Therein lies the sickness. Freud didn't see this at all.