The ego-created sense of lack or incompleteness, of not being whole
Extract of the book The Power of Now of Eckhart Tolle
Another aspect of the emotional pain that is an intrinsic part of the egoic mind is a deep-seated sense of lack or incompleteness, of not being whole. In some people, this is conscious, in others unconscious. If it is conscious, it manifests as the unsettling and constant feeling of not being worthy or good enough. If it is unconscious, it will only be felt indirectly as an intense craving, wanting and needing. In either case, people will often enter into a compulsive pursuit of ego gratification and things to identify with in order to fill this hole they feel within. So they strive* after possessions, money, success, power, recognition, or a special relationship, basically so that they can feel better about themselves, feel more complete. But even when they attain all these things, they soon find that the hole is still there, that it is bottomless. Then they are really in trouble, because they cannot delude themselves anymore. Well, they can and do, but it gets more
As long as the egoic mind is running your life, you cannot truly be at ease; you cannot be at peace or fulfilled except for brief intervals when you obtained what you wanted, when a craving has just been fulfilled. Since the ego is a derived sense of self, it needs to identify with external things. It needs to be both defended and fed constantly. The most common ego identifications have to do with possessions, the work you do, social status and recognition, knowledge and education, physical appearance, special abilities, relationships, personal and family history, belief systems, and often also political, nationalistic, racial, religious, and other collective identifications. None of these is you.
COMMENT by Atman Nityananda
they strive* after possessions, money, success, power, recognition, or a special relationship:
I will add also pleasures. According my own experience the ego causes this sense of lack, that something is missing here and now in order to drive us find something pleasurable to fill the hole. Desire for pleasure is what generates this sense of lack in order to drive us to seek some pleasurable experience. Moreover desire end ego are one and the same thing. I am talking about the vital rajasotamasic ego which what makes us identify with the body, the mental and emotional formations and the sense objects and situations. The essential nature of this vital ego is lust and desire.