Indian philosophies and it’s six points of view (darshana) vary slightly in many ways, as this knowledge was collected from different sources at different times and and places and based on different experiences.
Samkhya for example is very much a philosophy of Dualism (Dvaita – on which Patanjali’s Yoga Sutras are based on), based on the belief that there are two separate eternal forces, that where never created but exist, in their pure potentiality eternally. They are both real. These two forces are Purusha, the pure consciousness or soul the cosmos and of every living being that is unchangeable and does not have creative power – and Prakriti, the ever changing matrix of the cosmos, the core of the cosmos, the cosmos itself, in all it’s shapes and forms, both gross and subtle.
Prakriti consists of three qualities, or Gunas, which are in complete balance and pure potentiality as long as Prakriti and Purusha are separate.
These Gunas are Tamas (Inertia), Rajas (Movement) and Sattva (Illumination).
Purusha and Prakriti exist in an everlasting attraction to each other. At some stage, when the attraction becomes too strong, they begin to merge into each other.
When this happens, the perfect balance of the Gunas is disturbed. In an eternal effort to come back into a balance, the Gunas move, increase, decrease and begin the “dance” of evolution and life. The first evolute is created: Buddhi, or the higher mind. At this stage, the potential state of Prakriti is still in a very subtle form and Buddhi (or Mahat, the cosmic intelligence) becomes a discerning and intelligent force, born out of the imbalances of the gunas and closely connected to Purusha, the soul and pure consciousness. It doesn’t in itself have a consciousness but reflects the pure awareness of our self. Here there is access to all higher knowledge.
The second evolute emerges from Buddhi – Ahamkara, the I-Maker (Ego). Out of the intelligence of the Buddhi emerges another, more concrete and less subtle power of discernment. Ahamkara is able to distinguish Me from You. It compares. It judges.
Growing out of this instinct to compare and distinguish comes the lower mind, or Manas – a much less subtle force that we can sense – as well as the five subtle sense potentials through which Manas is working. These are the potential of hearing, seeing, feeling, tasting and smelling. And on a lower level still, situated in the gross body, are the corresponding sense organs – the eyes, ears, nose, skin, tongue and the organs of action – hands, feet, anus, sexual organs and mouth.
These consist of the gross (material) elements of fire, water, earth, air and space (ether).
So the evolution of any living thing, according to Samkhya, consists of Prakriti in it’s potential state, and her 23 evolutes.
From the dualistic (Dvaita) point of view, Purusha needs Prakriti in order to experience itself and live out any karmic impressions that may have accumulated. But it also has to emancipate itself from it, in order to be free. Maybe this can be compared to a mother guiding us through the experiences and lessons of life but eventually we need to become independant.
In Yoga, we are trying to free ourselves from this dependency on Prakriti by involution, by reversing the process of evolution, by going backward.
We are trying to access through the gross, physical body and work our way, via the nervous system, to our mind and eventually transcending our Ego mind to enter our Buddhi Nature. From here, we can feel the presence of our true soul, Purusha.
Vedanta on the other hand, from which the Bhadavad Gita draws in it’s dialogue between Arjuna and Krishna, is mostly (although not completely) based on the metaphysical concept of non duality (Advaita).
Only one pure state of consciousness exists that is the substance of the cosmos, the one supreme reality. This reality is called Brahman.
All living things are created from this one reality and are all connected.
In their individual state (ie our own individual souls) it is called Atman, although they are absolutely the same (much like the space inside a room and outside a room are the same – the only difference are the walls that make it hard to see out).
Everthing else, including our thoughts, emotions and the perception that we are separated from each other, is referred to as Maya (Illusion). This illusion comes from the distorted perception of our own reality, like a mirror that is warped by our own karmic imprints and caught in the web of cause and effect. Almost like we are in a dream, which we are witnessing but are not waking up from, and as long as we are in it, we believe it to be real.
Advaita Vedanta believes that if we can remove this veil of wrong perception and see clearly, experience, remember our own true divinity, we can experience the true bliss, happiness and unconditional love that is the true nature of Atman. Then we become free from a conditioned existence, where we can only be happy IF.. rather than in a true state of bliss. (Moksha).
Non Dualism also has a concept of evolution, as explained best through the model of Pancha Kosha (the 5 Sheaths or Bodies of Existence):
Here, we also begin with the lowest vibration, the densest of Sheaths that is most accessable to our perception, the Physical body (Anna Maya Kosha) and work our way internally toward our true inner nature.
In both cases, we need to have certain experiences that arise from the seeds of karmic imprints that have been planted at the beginning of time. And in both cases our destiny is to free ourselves from these karmic bondages and either emancipate ourselves or wake up from our cosmic dream.