The three lower principles that constitute our human existence are:
But in reality everything is the Divine.
The Mind is put forward by the Supermind as force and this force uses material force which one can call as Prakriti to create the material universe. The Mind when it is yoked to the Supermind always reflects the Universal Truth, but when it is not yoked to the Supermind, creates divisions and dualities and the perception that we usually have in this world.
Hence, as Sri Aurobindo says:
Consequently, the triple world that we live in, the world of Mind-Life-Body, is triple only in its actual accomplished evolution. Life involved in Matter has emerged in the form of thinking and mentally conscious life. But with Mind, involved in it and therefore in Life and Matter, is the Supermind, which is the origin and ruler of the other three, and this also must emerge.
Life is the form of the Cosmic Divine that is born, grows, dies and is born again. It is never destroyed but just changes forms. This is not only true of the material body but also of the feeling-body or the thought body. So one can say that all renews itself, nothing perishes. Even if all forms perish, the Cosmic Divine still exists. So life is nothing but the force that builds, maintains and destroys all the forms in the world, from matter to man.
So Sri Aurobindo says that everything is life, including matter, plant, animal and man. There may be differences in what is expressed, but ultimately everything is life. This life force is what is called the Chit Shakti or consciousness force. In his words:
That Force is fundamentally the Chit-Tapas or Chit-Shakti of the Vedanta, consciousness-force, inherent conscious force of conscious-being, which manifests itself as nervous energy full of submental sensation in the plant, as desire-sense and desire-will in the primary animal forms, as self-conscious sense and force in the developing animal, as mental will and knowledge topping all the rest in man. Life is a scale of the universal Energy in which the transition from inconscience to consciousness is managed; it is an intermediary power of it latent or submerged in Matter, delivered by its own force into submental being, delivered finally by the emergence of Mind into the full possibility of its dynamis.
So Aurobindo is saying are saying that matter evolves into life and life evolves into mind and hence mind should evolve to supermind. As Aurobindo says:
The material Energy that aggregates, forms and disaggregates is the same Power in another grade of itself as that Life-Energy which expresses itself in birth, growth and death, just as by its doing of the works of Intelligence in a somnambulist subconscience it betrays itself as the same Power that in yet another grade attains the status of Mind; its very character shows that it contains in itself, though not yet in their characteristic organisation or process, the yet undelivered powers of Mind and Life.
Further he says:
Life then reveals itself as essentially the same everywhere from the atom to man, the atom containing the subconscious stuff and movement of being which are released into consciousness in the animal, with plant life as a midway stage in the evolution. Life is really a universal operation of Conscious-Force acting subconsciously on and in Matter; it is the operation that creates, maintains, destroys and re-creates forms or bodies and attempts by play of nerve-force, that is to say, by currents of interchange of stimulating energy to awake conscious sensation in those bodies.
In this operation there are three stages; the lowest is that in which the vibration is still in the sleep of Matter, entirely subconscious so as to seem wholly mechanical; the middle stage is that in which it becomes capable of a response still submental but on the verge of what we know as consciousness; the highest is that in which life develops conscious mentality in the form of a mentally perceptible sensation which in this transition becomes the basis for the development of sense-mind and intelligence. It is in the middle stage that we catch the idea of Life as distinguished from Matter and Mind, but in reality it is the same in all the stages and always a middle term between Mind and Matter, constituent of the latter and instinct with the former.
Life is an operation of Conscious-Force which is neither the mere formation of substance nor the operation of mind with substance and form as its object of apprehension; it is rather an energising of conscious being which is a cause and support of the formation of substance and an intermediate source and support of conscious mental apprehension.It supports and liberates into action the apprehensive consciousness of existence called mind and gives it a dynamic instrumentation so that it can work not only on its own forms but on forms of life and matter; it connects, too, and supports, as a middle term between them, the mutual commerce of the two, mind and matter.
It is therefore this nerve-energy which we usually mean when we talk of Life; it is the Prana or Life-force of the Indian system. But nerve-energy is only the form it takes in the animal being; the same Pranic energy is present in all forms down to the atom, since everywhere it is the same in essence and everywhere it is the same operation of Conscious-Force,—Force supporting and modifying the substantial existence of its own forms, Force with sense and mind secretly active but at first involved in the form and preparing to emerge, then finally emerging from their involution. This is the whole significance of the omnipresent Life that has manifested and inhabits the material universe.