We can say there are three layers of “self” overlaid on a core of being. The core is a quantum of “light.” Light means sentience, consciousness – the thing that “illuminates” and allows us to perceive and see. This is commonly called a “soul” or ātmān or jīva.
The first layer over the soul is ahaṁkāra which sometimes gets translated as “ego” or “false ego.” But really is the aquired quality of ego. The soul itself is the true core of “I-ness” which is “ego” in a positive sense. Ahaṁkāra on the other hand is the negative effect of I-ness, which is “I will ___ for myself.” Its “ego” in the sense of being self-centered and self-serving, not in the sense of having identity. Identity is a part of the core itself, the light which is consciousness, comes from a distinct point of identity. The first layer over the soul, ahaṁkāra is the first negative ramification of misusing or misunderstanding identity… it is the quality of being self-centered and self-serving.
In astrology, the Sun represents this layer. The Sun shows the focal point of our idenity, It’s condition and placement in the houses, and signs, amongst aspects, conjunctions and yogas, fills in the “____” in the ahaṁkāra phrase “I will ____ for myself.” For example, “I will be creative and smart for myself” could be implied by the Sun in the 5th house. The blessedness or cursedness of the Sun in the 5th house implies how much good or bad karma this will generate. Very very blessed, the person could think “I will learn how to be less selfish by learning the true nature of the world.” Very cursed, the person could think, “I will learn how to manipulate people and things for my exploitation.”
The second layer over the soul is an emotional layer. An intellectual layer also exists (represented by Mercury), but it is so integral to the ego layer (Mercury is always so close to the sun) that it’s not considered very separately. Rather its sort of skipped in this analysis and we go immediately to the emotional layer represented by the Moon.
Actually we also neglect the core in astrology and subsume it into the Sun’s symbolism. This is because the core is rather removed from the whole material, karmic affair that astrology describes. It is the projections of the soul, into three layers, which are really affected by karma, and thus describable by astrology.
The second layer (moon) stores all our desires, and all the feelings that arise as a result of fulfilling or failing to fulfill those desires.
The third layer over the core living entity is the physical body. This is represented by the ascendant.