The following passage is from Sri Aurobindo's The Life Divine (10th ed.), , Chapter XXIII, The Double Soul in Man. It refers to the two sides of human nature; the subliminal spiritual aspect which is in touch with the Divine, and the small superficial surface or lower desire aspect. While it is simplistic to take this dualism as an absolute, since reality is multifaceted, as a general pragmatic statement it is useful, for it describes the tensions that come into play between material/embodied/egotistic and spiritual/Higher Self. This duality is described in almost every spiritual-mystical teaching. The outer or lesser being is usually described as "animal soul" (an insult to the animal kingdom I feel, and reflecting an inherent species that. like sexism, is a part of the chauvinistic orientation of even the best esoteric teachings) as opposed to the Divine Soul, the body or flesh as opposed to the spirit, the sinful nature as opposed to the saintly nature, and so on.
In Sri Aurobindo's the outer surface nature is called the Desire Soul. This is exactly equivalent to what all pop-gurus call the "ego". Of course "ego" is a very misleading term, since it is given one meaning by Freud, another by Jung, another by Blavatsky, another by the pop-gurus, and so on. Hence the prefence in this context of the Aurobindonian term. (Of course it must be understood that by "desire" is meant here the lower desires, not the higher longings)
As always when dealing with long passages of Sri Aurobindo's profound but dense material, I have, for ease of understanding, broken the following quote into a number of smaller paragraphs and notations
"...there is a double soul or psychic term in us, as every other cosmic principle in us is also double.
For we have two minds,one the surface mind of our expressed evolutionary ego, the superficial mentality created by us in our emergence out of Matter,
another a subliminal mind which is not hampered by our actual mental life and its strict limitations, something large, powerful and luminous, the true mental being behind that superficial form of mental personality which we mistake for ourselves.
So also we have two lives,one outer, involved in the physical body, bound by its past evolution in Matter, which lives and was born and will die,
the other a subliminal force of life which is not cabined between the narrow boundaries of our physical birth and death, but is our true vital being behind the form of living which we ignorantly take for our real existence.
Even in the matter of our being there is this duality;for behind our body
we have a subtler material existence which provides the substance not only of our physical but of our vital and mental sheaths and is therefore our real substance supporting this physical form which we erroneously imagine to be the whole body of our spirit.
So too we have a double psychic entity in us,the surface desire-soul which works in our vital cravings, our emotions, aesthetic faculty and mental seeking for power, knowledge and happiness,
and a subliminal psychic entity, a pure power of light, love, joy and refined essence of being which is our true soul behind the outer form of psychic existence we so often dignify by the name.
It is when some reflection of this larger and purer psychic entity comes to the surface that we say of a man, he has a soul, and when it is absent in his outward psychic life that we say of him, he has no soul.
The external forms of our being are those of our small egoistic existence;
the subliminal are the formations of our larger true individuality....The subliminal mind in us is open to the universal knowledge of the cosmic Mind,
the subliminal life in us to the universal force of the cosmic Life,
the subliminal physicality in us to the universal force-formation of cosmic Matter;
...So too is the subliminal soul in us open to the universal delight which the cosmic soul takes in its own existence and in the existence of the myriad souls that represent it and in the operations of mind, life and matter by which Nature lends herself to their play and development;
but from this cosmic delight the surface soul is shut off by egoistic walls of great thickness which have indeed gates of penetration, but in their entry through them the touches of the divine cosmic Delight become dwarfed, distorted or have to come in masked as their own opposites.
It follows that in this surface or desire-soul there is no true soul-life, but a psychic deformation and wrong reception of the touch of things. The malady of the world is that the individual cannot find his real soul,....
If he could find that essence, he would find also the one universal being, power, conscious existence and delight even in this throng of touches and impressions; the contradictions of what seems would be reconoiled in the unity and harmony of the Truth that reaches out to us in these contacts. At the same time he would find his own true soul and through it his self, because the true soul is his self's delegate and his self and the self of the world are one.
But this he cannot do because ofthe egoistic ignorance in the mind of thought,
the heart of emotion,
the sense which responds to the touch of things not by a courageous and whole-hearted embrace of the world, but bya flux of reachings and shrinkings,according as the touch
cautious approaches or eager rushes
and sullen or discontented or panic or angry recoilspleases or displeases,
comforts or alarms,
satisfies or dissatisfies.
It is the desire-soul that by its wrong reception of life becomes the cause of a triple misinterpretation of the rasa, the delight in things, so that, instead of figuring the pure essential joy of being, it comes rendered unequally into the three terms of pleasure, pain and indifference. "