Sva-svami-saktyoh svarupopalabdhi-hetuh samyogah.(II-23)
Sva = Prakrti; Svami = Purusa; Saktyoh= powers; Svarup = own from; Upalabdhi = gaining; hetuh= cause; Samyogah = union.
The purpose of the coming together of the Purusa and Prakrti is gaining by the Purusa of the awareness of his true nature and theenfoldment of powers inherent in him and Prakrti.
To understand this profound sutra about 'why' of the creation, we have to understand the terms Purusa or the Seer (referred to here as Swami) and Prakrti or the Seen (termed here as Sva).
Each object in this universe (including the universe itself) has two aspects-exoteric and esoteric, apparent and hidden, from and essence. The body is the from and soul, the essence. Even the non-living, the mineral world has its soul, through very rudimentary. It has its own consciousness. Famous Indian scientist Sir Jagdishchandra Bose, while demonstrating through his experiments in England, the life in plants, showed how ever a piece of Lead responded to the stimulation. It was so unbelievable that one of the scientists exclaimed, "Mr Bose, What are you trying to show!"
So, consciousness is universal. It may be less manifest in stone and more in a man and still more in a evolved man. And when it is manifest fully, the pure consciousness we call it God. This consciousness, in Yoga, is termed as Purusa.
Consciousness or Purusa (the essence) is one aspect of the universe. The other aspect is the 'from'. Astone, a flower, a cat and a man represent forms of various kingdoms- the mineral world, the plants, the animal world and the human beings. This outer aspect, the form, is called Prakrti.
Everything in this universe is evolving continuously. Darwin's theory tells how man evolved from monkey. But this refers only to the evolution of the form. What about the essence, the consciousness? Some scientists do not evenrecognize this aspect of the universe. In a complete evolution the form and the essence both have to evolve hand by hand.
But according to yogic philosophy consciousness is eternal, complete. How can it evolve then? Yet there is a difference between the consciousness in a tree and in a cow. The difference is that of manifestation. In the later it is more manifest. Thisenfoldment of consciousness is different from what we call evolution.
Let us take the example of the Sun covered with clouds. The clouded Sun sheds less light but shines brilliantly when clouds disperse. The Sun has not evolved here when it has come out of the clouds. Its bright light was there all the time. Similarly the consciousness, ever bright, is to be unfolded in the process of evolution. In other words, the Purusa has to go on manifesting itself till it is free from all the limitations, till it achieves its true nature, its Svarupa.
The hurdle in the enfoldment of the consciousness is the form in which it is trapped. Though it is certain that a stone will turn into a plant in an animal in due course but it will take a along long time due to the inadequate, limited form. Whereas for a man, due to the wonderful form it has got with a sophisticated brain, it is easier to evolve fast and reach the divinity by going beyond the form itself. That is why the human birth is considered so precious.
The gist of the present sutra as per Dr Taimini (as given in his book Science of Yoga) is given below.
It answers the question: Why is Purusa brought into contact with Prakrti?
The answer is: To unfold the powers latent in Prakrti and himself and to enable him to gain Self-realization.