The ego is hydra-headed and expresses itself in numberless ways. It lives upon any type of ignorance. Pride is the specific feeling through which egoism manifests. A person can be proud of the most unimportant and silly things.
Instances are known, for example, of people developing their nails to an abnormal length and preserving them, despite much inconvenience to themselves, for no other reason than to assert separateness from others. The ego must magnify its attainments in grotesque ways if it is to live in them.
Direct assertion of the ego through self-display in society is very common; but if such direct assertion is prohibited by the rules of conduct, the ego has a tendency to seek the same result through the slander of others. To portray others as evil is to glorify oneself by suggesting a comparison — a comparison the ego would willingly develop, though it often restrains itself from doing so.
The ego is activated by the principle of self-perpetuation and has a tendency to live and grow by any and all means not closed to it. If the ego faces curtailment in one direction, it seeks compensating expansion in another. If it is overpowered by a flood of spiritual notions and actions, it even tends to fasten upon this very force, which was originally brought into play for the ousting of the ego.
If a person attempts to cultivate humility in order to relieve himself of the monstrous weight of the ego and succeeds in doing so, the ego can, with surprising alacrity, transfer itself to this attribute of humility. It feeds itself through repeated assertions like "I am spiritual," just as in the primary stages it achieved the same task by assertions like "I am not interested in spirituality."
Thus arises what might be called a spiritual ego, or an ego that feels its separateness through the attainment of things considered to be good and highly spiritual. From the truly spiritual point of view, this type of ego is as binding as the primary and crude ego, which makes no such pretensions.
In fact, in the more advanced stages of the path, the ego does not seek to maintain itself through open methods but takes shelter in those very things that are pursued for the slimming down of the ego. These tactics of the ego are very much like guerrilla warfare and are the most difficult to counteract.
The ousting of the ego from consciousness is necessarily an intricate process and cannot be achieved by exercising a constantly uniform approach. Since the nature of the ego is very complicated, an equally complicated treatment is needed to get rid of it. As the ego has almost infinite possibilities for making its existence secure and creating self-delusion, the aspirant finds it impossible to cope with the endless cropping up of fresh forms of the ego. He can hope to deal successfully with the deceptive tricks of the ego only through the help and grace of a Perfect Master. (Discourses, pp. 170-171)