Cause of Ego

The cause of ego is that while by Its double power of Vidya and Avidya the Spirit dwells at once in the consciousness of multiplicity and relativity and in the consciousness of unity and identity and is therefore not bound by the Ignorance, yet It can, in mind, identify Itself with the object in the movement, absorbingly, to the apparent exclusion of the Knowledge which remains behind, veiled at the back of the mentality. The movement of Mind in Nature is thus able to conceive of the object as the reality and the Inhabitant as limited and determined by the appearances of the object. It conceives of the object, not as the universe in one of its frontal appearances, but as itself a separate existence standing out from the Cosmos and different in being from all the rest of it. It conceives similarly of the Inhabitant. This is the illusion of ignorance which falsifies all realities. The illusion is called ahaṁkāra, the separative ego-sense which makes each being conceive of itself as an independent personality.

The result of the separation is the inability to enter into harmony and oneness with the universe and a consequent inability to possess and enjoy it. But the desire to possess and enjoy is the master impulse of the Ego which knows itself obscurely to be the Lord, although owing to the limitations of its relativity, it is unable to realise its true existence. The result is discord with others and oneself, mental and physical suffering, the sense of weakness and inability, the sense of obscuration, the straining of energy in passion and in desire towards self-fulfilment, the recoil of energy exhausted or disappointed towards death and disintegration.

Desire is the badge of subjection with its attendant discord and suffering. That which is free, one and lord, does not desire, but inalienably contains, possesses and enjoys

Ref : Isha Upanishad