Some individuals are drawn toward the immobile, silent Akshara Purusha, and they pursue a path through renunciation of the world and silent absorption intended to bring them to a state of union with that aspect of the divine existence. Others are fully involved in the life of the world and try to find their fulfilment of the Kshara Purusha within the scope and based on the terms of that life. Each tends to hold the other as following an illusory option. The Gita’s position that the Purushottama is greater than each of them and reconciles their apparent opposition implies that neither of these, with their focus on one aspect or the other, is able to fully provide the salvation the Gita asks us to seek .
It can be noted that the theme of an integrated realisation incorporating two types of knowledge arises already in the Upanishads. The Isha Upanishad in particular makes this point clear: “Into a blind darkness they enter who follow after the Ignorance, they as if into a greater darkness who devote themselves to the Knowledge alone….He who knows That as both in one, the Knowledge and the Ignorance, by the Ignorance crosses beyond death and by the Knowledge enjoys Immortality.” (Isha Upanishad, v. 9, 11)
“Into a blind darkness they enter who follow after the Non-Birth, they as if into a greater darkness who devote themselves to the Birth alone….He who know That as both in one, the Birth and the dissolution of Birth, by the dissolution crosses beyond death and by the Birth enjoys Immortality.” (Isha Upanishad v. 12, 14)
Sri Aurobindo takes up the point of the Gita: “But the Divine is neither wholly the Kshara, nor wholly the Akshara. He is greater than the immutable Self and he is much greater than the Soul of mutable things. If he is capable of being both at once, it is because he is other than they…, the Purushottama above all cosmos and yet extended in the world and extended in the Veda, in self-knowledge and in cosmic experience. And whoever thus knows and sees him as the Purushottama, is no longer bewildered whether by the world-appearance or by the separate attraction of these two apparent contraries.”
The knowledge which unites the two aspects, “…restores the integral reality of the Divine.” “Divine in the equality of his imperturbable self-existence, one in it with all objects and creatures, he brings that boundless equality, that deep oneness down into his mind and heart and life and body and founds on it in an indivisible integrality the trinity of divine love, divine works and divine knowledge. This is the Gita’s way of salvation.”
Sri Aurobindo, Essays on the Gita, Second Series, Part II, Chapter 15, The Three Purushas, pp. 433-434
and Sri Aurobindo, The Upanishads, pp. 21-23, Isha Upanishad