The Shwetashwatara Upanishad decribes two birds sitting on a common tree, one eating the sweet fruit and the other not eating but observing. This is an illustration of the relationship of the soul and the nature. The soul observes and sanctions the actions of the nature, while the nature carries out the actions through the interplay of the three Gunas and the “pairs of opposites” which give rise to the duality that we experience during action in the world. The Bhagavad Gita provides extensive and detailed analysis of the operation of the three Gunas, tamas, rajas and sattwa. Each of the Gunas has characteristics that represent one “pole” of one of the pair of opposites, and thus, they are constantly balancing against each other and bringing about the interplay of light and dark, action and inaction, calm and disturbance that we experience in our lives.
The soul in observing and thereby supporting the action of nature becomes enamoured of the action and gets involved in the changes provided by the constantly interacting Gunas. The focus becomes so all-encompassing that the soul forgets its true nature of divinity and believes itself to be bound within the natural play. Sri Aurobindo observes: “The acceptance of the instrumental ego-consciousness and the will-to-desire are the initial consent of the self to the lapse into the lower ranges of experience in which it forgets its divine nature of being; the rejection of these things, the return to free self and the will of the divine delight in being is the liberation of the spirit.”
This still leaves, however, the nature unreformed and bound. “A complete liberation from the ego and the will of desire must bring with it a superiority to the qualitative modes of the inferior Nature, traigunyatitya, a release from this mixed and discordant experience, a cessation or solution of the dual action of Nature. But on this side too there are two kinds of freedom. A liberation from Nature in a quiescent bliss of the spirit is the first form of release. A farther liberation of the Nature into a divine quality and spiritual power of world-experience fills the supreme calm with the supreme kinetic bliss of knowledge, power, joy and mastery. A divine unity of supreme spirit and its supreme nature is the integral liberation.”
Sri Aurobindo, The Synthesis of Yoga, Part Four: The Yoga of Self-Perfection, Chapter 9, The Liberation of the Nature, pg. 655-656