ego-consciousness is a prime feature of the territory he was exploring.
It is the tool.
Not all that seems true to even the most earnest and sincere investigator's consciousness is necessarily accurate knowledge. Much that passes for knowledge among human beings is actually, upon closer and more critical inspection, merely prejudice or belief based on distortion, bias, hearsay, speculation, or pure fantasy. Beliefs pass as knowledge and are clung to as reliable certainties. "I believe in order that I may understand," a famous remark from St. Augustine, may sound strange to our modern ears today, and this is often the case when people begin to speak about psychological reality.
the ego is the subject of all personal acts of consciousness
a connection to the ego is the necessary condition for making anything conscious
the ego is a kind of mirror in which the psyche can see itself and can become aware. The degree to which a psychic content is taken up and reflected by the ego is the degree to which it can be said to belong to the realm of consciousness.
The ego contains our capacity to master large amounts of material within consciousness and to manipulate them. It is a powerful associative magnet and an organizational agent. Because humans have such a force at the center of consciousness, they are able to integrate and direct large quantities of data. A strong ego is one that can obtain and move around in a deliberate way large amounts of conscious content. A weak ego cannot do very much of this kind of work and more easily succumbs to impulses and emotional reactions. A weak ego is easily distracted, and as a result consciousness lacks focus and consistent motivation.
The two major attitudes (introversion and extroversion) and the four functions (thinking, feeling, sensation and intuition) have a strong influence upon the ego's orientation as it undertakes its adaptive tasks and requirements. The ego's innate disposition toward assuming one of these attitudes and functions forms its characteristic stance toward the world and toward assimilating experience.
Collisions with reality awaken the nascent ego's potentiality and challenge it to relate to the world. Such collisions also interrupt the psyche's participation mystique with the surrounding world. Once aroused, the ego must adapt itself to reality by whatever means are available. Jung theorized that there are four such means or functions of the ego, each of which could be oriented by either an introverted (ie., inward-looking) or extroverted (outward looking) attitude. After a certain amount of ego development has taken place, the person's innate tendency to orient to the world, within and without, will reveal itself in certain definite ways. Jung argued that the ego has a inborn, genetic tendency to prefer one particular type of attitude and function combination and to rely secondarily on another complimentary combination for balance, with a third and fourth remaining less used and consequently less available and developed. The combinations make up what he called "psychological types."
As a rule one of these two best functions is extroverted and the other is introverted, the extroverted function giving a reading of external reality and the introverted function providing information about what is going on within.
Broadly speaking, it is the contents of the unconscious that curtail the free will of the ego. The Apostle Paul expressed this classically when he confessed: "I do not understand my own actions. For I do not what I want, but I do the very thing that I hate... I can will what is right but I cannot do it." Demons of contrariness conflict with the ego. Jung concurs: "just as circumstances and outside events "happen" to us and limit our freedom so the self acts upon the ego like objective occurrence, which free will can do very little to alter." When the psyche takes over the ego as an uncontrollable inner necessity, the ego feels defeated and has to face the requirements of accepting its inability to control inner reality just as it has to come to this conclusion regarding the larger surrounding social and physical worlds. Most people in the course of their lives come to realize that they cannot control the external world, but fairly few become conscious that inner psychic processes are not subject to ego control either.