All the orthodox schools of Hindu philosophy postulate that the universe of matter and energy has evolved out of primordial nature or prakriti. The purusha or spirit, is a conscious and intelligent entity and is distinct from prakriti or its derivatives. In monistic schools of thought, nature is supposed to be a superimposition on the eternal spirit which is non-dual. However, nature and its evolutes are admitted as phenomenal reality even by the monistic schools.
Within prakriti, the Samkhya, Yoga and Vedanta schools postulate twenty four categories or gunas. They are:
Above these categories of nature or prakriti stands the purusha or the intelligent principle.
One may wonder that this categorisation does not seem to recognise energy in its various forms as a fundamental entity. The pancha bhutas are- prithvi or earth, apas or water, tejas or fire, vayu or air and akasha or ether. The other categories also do not refer to either the concept of energy or the different forms of energy. Purusha whose nature is denned as pure consciousness is held as distinct from prakriti or nature. Therefore, the place of energy in the scheme of things is not very clear.
While the superficial examination of the categories of prakriti or nature would lead one to the above conclusion a deeper study would appear to indicate that the entire universe of matter-energy is included in the categories of prakriti according to Samkhya or Vedanta. Let us examine the pancha bhutas, which are considered to be the five primary constituents of matter or the universe, in greater detail.
The element akasha, which is translated as space or ether, is responsible for shabda or sound perception by the sense-organ srotra or the ear. We know that sound requires a medium for its propagation. Speech is conveyed to the ears through air. There is no sound propagation through a vacuum. What is actually propagated as a sound wave is only the mechanical energy or vibration through the successive particles of the medium. The particles of the medium in contact with the tympanum transfer this energy to it, and these impulses are then carried by the auditory nerves to the relevant centre in the brain which interprets it as sound. This mechanical energy of vibration is derived only from gravitational energy as taught by science. Therefore, akasha or space, through which the gravitational energy acts, is considered to be the conveyor of sound. That is why sound or shabda is considered to be the inherent quality of akasha or space, which could be deemed as representing that form of energy known as gravitational energy.
Vayu literally means air or anything in the gaseous form. Sparsa or the sense of touch is considered to be its quality and it is recognised by the sense organ 'tvak' (touch). The word 'Vayu' is derived from the root to blow, to go, or to move. Movement of energy is conveyed by this word. In yoga the term has a special meaning. It represents the bio-energy. It is experienced as impulses of sensation through the nervous system. In the categories of prakriti the word vayu can be deemed to represent electromagnetic energy, whose distinguishing feature is movement, the velocity being that of light and the maximum of anything in the universe. This could be propagated through empty space as heat or light, and through specific conducting media such as electrical energy.
Whatever be the mode of propagation outside the human system, when the energy impinges on the skin or the organ of touch, as heat or electrical shock, the impulses are carried through the sensory nerves to the corresponding centre in the brain and recognised as such. Touch or contact (sparsa) is essential for this knowledge and this quality is attributed to vayu or energy in motion. The same is true of the sensation of touch communicated to the skin by any moving object including air. Therefore, vayu should be considered as representing those forms of energy designated in physics as the electromagnetic spectrum, with wavelengths exceeding those of visible light and electrical energy communicated through conducting media. It is noteworthy that all sensations carried to the brain by the nervous system are considered to be in the nature of electrical impulses.
The next element is tejas, which is derived from the root tej, to sharpen or to whet. In the matter-energy complex (which, as modern science has proved, are inter-convertible), this element represents that entity which provides definition to any material object. The perception of rupa or form is associated with this bhuta, and the sense organ responsible for this perception is the eye or chakshu. Therefore, tejas is identical with light-energy in the visible spectrum, which is received and recognised by the chakshu or the eye. It could be deemed as covering even electromagnetic energy of smaller wave lengths, such as ultraviolet and X-rays. Its quality is rupa, form or definition.
Apas or fluid, refers to the liquid forms of matter which are characterised by fluidity. The sense of taste is imparted by the solution of any substance on the tongue, the changes induced thereby in the taste-buds of the tongue being conveyed through the sensory nerves to the corresponding brain centre. Therefore, rasa or taste is the perception attributed to the element apas or fluid, the tongue being the sense organ concerned. Apas is actually derived from the root 'Aap', to pervade.
The remaining element in the matter-energy complex is prithvi or bhumi (derived from the root bhu, to be or to exist). This represents all solids to which is attributed the quality of gandha or smell. The root 'gandha', meaning smell, also appears to be significant. The sense of smell arises by the impinging of the particles of matter on the sensitive cells within the nose, the changes arising therefrom being recognised as smell by the corresponding brain centre, which receives the sensory impulses through the nerves from the olfactory region of the nose.
Thus the pancha mahabhutas or the five great elements really represent the universe of matter-energy. Apart from this there is the element of sentience or consciousness which is the fire element in all living beings. In the Gita, it is termed as paraprakriti about which the following definition is given:
"Earth, water, fire, air, ether, mind and intellect and also ego-sense; these are the eight-fold division of my nature. This is inferior. Know my other nature, the higher, Oh Mighty-Armed, the life-element by which the universe is upheld". (7:4-5)
The higher nature is pure consciousness. Consciousness is the substratum of the matter-energy universe and it is manifested as sentience in all living beings. It upholds the functions of the lower forms of energy. It is the inseparable counterpart of the eternal reality designated as Brahman and is non-different from it. It is this conscious energy which activates the mind, intellect and ego-sense, which are the instruments of perception in living beings.
Scientists are still searching for a unified theory of energy which will explain the behaviour of the two basic forms of energy- gravitational and electromagnetic, through a single law or theorem. Prana and energy of consciousness are most subtle, pervasive and the substratum of the entire matter-energy universe. They are the natural shakti or energy aspect of Brahman, the supreme reality. In the Svetasvatara Upanishad it is said:
"The supreme energy of God or Brahman is heard of as manifold in nature - knowledge, strength and activity (sushumna, ida and pingala)".
It could be considered that the energy of consciousness is designated here by jnana or knowledge. Mechanical energy derives from gravitational energy as bala or strength and electromagnetic energy which is within universal phenomena as kriya or activity. Scientific research in the future may perhaps unveil the mysteries of this life energy and energy of consciousness. This paper is purely suggestive and seeks to reconcile the important fact of the universe of matter-energy with the orthodox categorisation of prakriti or nature.