Samkhya (Sanskrit: साङ्ख्य, IAST: sāṅkhya) is a dualistic āstika school of Indian philosophy, regarding reality and human experience as being constituted by two independent ultimate principles, puruṣa (‘consciousness’ or spirit); and prakṛti, (cognition, mind and emotions, and nature or matter).
Puruṣa is the witness-consciousness. It is absolute, independent, free, imperceptible, unknowable through other agencies, above any experience by mind or senses and beyond any words or explanations. It remains pure, “non-attributive consciousness”. No appellations can qualify purusha, nor can it be substantialized or objectified. Purusha is considered as the first concept of Sankhya philosophy. Pur means ‘city’. Sheta means ‘dwelling, living, existing’. Purusha is that pure Consciousness that exists lives, dwells in the city of senses. The body is a city of senses. Purusha can be called pure Consciousness. Purusha is the universal principle that is unchanging, uncaused, and present everywhere. Purusha is the witness in which everything is occurring. This conscious energy of Purusha is related to Shiva, the male energy.
Prakriti is the creative power of God, the aspect of Spirit as creative Mother Nature—Pure Nature or Holy Ghost. As such it is imbued with the seed of twenty-four attributes, the workings of which give birth to all manifestation. From Prakriti evolve (1) chitta (intelligent consciousness, the power of feeling—the basic mental consciousness—Sankhya’s Mahat-tattva), inherent in which are (2) ahamkara (ego); (3) buddhi (discriminative intelligence); and (4) manas (sense mind). From chitta, polarized by manas and buddhi, arise five causal creative principles (panchatattvas) that are the quintessence and root causes of the remaining twenty evolutes of creation.
Jiva (‘a living being’) is that state in which purusha is bonded to prakriti. Human experience is an interplay of purusha-prakriti, purusha being conscious of the various combinations of cognitive activities. The end of the bondage of Purusha to prakriti is called liberation or kaivalya (Isolation) by the Samkhya school.
Samkhya’s epistemology accepts three of six pramanas (‘proofs’) as the only reliable means of gaining knowledge, as does yoga. These are pratyakṣa (‘perception’), anumāṇa (‘inference’) and śabda (āptavacana, meaning, ‘word/testimony of reliable sources’). Sometimes described as one of the rationalist schools of Indian philosophy, this ancient school’s reliance on reason was exclusive but strong.
Puruṣa and Prakṛti
Samkhya makes a distinction between two “irreducible, innate and independent realities,” Purusha, the witness-consciousness, and prakṛti, “matter,” the activities of mind and perception. According to Dan Lusthaus,
“In Sāṃkhya puruṣa signifies the observer, the ‘witness’. Prakṛti includes all the cognitive, moral, psychological, emotional, sensorial and physical aspects of reality. It is often mistranslated as ‘matter’ or ‘nature’ – in non-Sāṃkhyan usage it does mean ‘essential nature’ – but that distracts from the heavy Sāṃkhyan stress on prakṛti’s cognitive, mental, psychological and sensorial activities. Moreover, subtle and gross matter are its most derivative byproducts, not its core. Only prakṛti acts.” 
Prakriti is material and it includes everything seen and unseen. Vivekananda explains, “What we call matter in modern times was called … bhutas, the external elements. There is one element which according to them, is eternal; every other element is produced out of this one. It is called akasha. … Along with this element, there is the primal energy called prana. Prana and akasha combine and recombine and form the elements out of them. … The akasha, acted upon by the repeated blows of prana, produces vayu, or vibrations … giving rise to heat, tejas. Then this heat ends in liquefaction, apah. … All that we know in the form of motion, vibration, or thought is a modification of the prana, … and everything that we know in the shape of matter, … is a modification of the akasha. … You have never seen force without matter, or matter without force; what we call force and matter are simply the gross manifestations of these same things, which, when superfine, are called prana and akasha. Prana you can call in English life, the vital force; but you must not restrict it to the life of man; at the same time you must not identify it with Spirit, atman. … Creation cannot have either a beginning or an end; it is an eternal ongoing.”
From the union of purusha and prakriti, Samkhya says, the insentient prakriti appears sentient. After stratifying the mental processes of cognition into various categories, the theory says that “Just as a picture does not exist without a substrate, or a shadow without a post or the like, so too the cognitive apparatus does not subsist supportless, without what is specific, that is, a subtle body (linga sarira). Formed for the sake of the spirit’s purpose, the subtle body acts like a dramatic actor, on account of the connection of “causes and effects” and by union with the all-embracing power of prakriti. … This evolution from the will down to the specific elements, is brought about by the modifications of prakriti. This work is done for the emancipation of each spirit, and thus is for another’s sake, though appearing as if it were for the sake of prakriti herself.” Vivekananda amplifies this passage from Samkhya as follows. “Why does nature do all this? Nature is undergoing all these changes for the development of the soul; all this creation is for the benefit of the soul so that it may be free. This immense book which we call the universe is stretched out before man so that he may read; and he discovers eventually that he is an omniscient and omnipotent being.”5 Thus, according to Samkhya, the purusha has somehow become identified with prakriti and this is the source of bondage. The role of prakriti is to liberate us from this identification. Kapila, the author of Samkhya, says there is no need to postulate the existence of “God”, if we take this word to mean “The First Cause”. Causation is a concept and as such is a mental evolute. In this sense, purusha and prakriti are both eternal as they are not mental evolutes. Such a startling conclusion in this ancient period is fascinating in itself. It echoes the conclusions of modern astrophysics.
In his book, A Brief History of Time, the celebrated physicist Stephen Hawking writes, “The idea that space and time may form a closed surface without boundary also has profound implications for the role of God in the affairs of the universe. With the success of scientific theories in describing events, most people have come to believe that God allows the universe to evolve according to a set of laws and does not intervene in the universe to break these laws. However, the laws do not tell us what the universe should have looked like when it started – it would still be up to God to wind up the clockwork and choose how to start it off. So long as the universe had a beginning, we could suppose it had a creator. But if the universe is really completely self-contained, having no boundary or edge, it would have neither beginning nor end: it would simply be. What place, then, for a creator?”
Prakṛti is the first cause of the world of our experiences. Since it is the first principle (tattva) of the universe, it is called the pradhāna, but, as it is the unconscious and unintelligent principle, it is also called the jaDa. It is composed of three essential characteristics (trigunas). These are:
Sattva – poise, fineness, lightness, illumination, and joy;
Rajas – dynamism, activity, excitation, and pain;
Tamas – inertia, coarseness, heaviness, obstruction, and sloth.
Unmanifested prakriti is infinite, inactive, and unconscious, with the three gunas in a state of equilibrium. This equilibrium of the gunas is disturbed when prakṛti comes into contact with consciousness or Purusha, giving rise to the manifestation of the world of experience from unmanifested prakṛti. Prakriti becomes manifest as twenty-three tatvas:
The five sensory capacities; the five action capacities; and the five “subtle elements” or “modes of sensory content:” (tanmatras: form (rūpa), sound (shabda), smell (gandha), taste (rasa), touch (sparsha)), from which the five “gross elements” or “forms of perceptual objects” emerge (earth (prithivi), water (jala), fire (Agni), air (Vāyu), ether (Ākāsha)).
Prakriti is the source of our experience; it is not “the evolution of a series of material entities,” but “the emergence of experience itself.” It is description of experience and the relations between its elements, not an explanation of the origin of the universe.
All prakriti has these three gunas in different proportions. Each guna is dominant at specific times of day. The interplay of these gunas defines the character of someone or something, of nature and determines the progress of life. The Samkhya theory of gunas was widely discussed, developed and refined by various schools of Indian philosophies. Samkhya’s philosophical treatises also influenced the development of various theories of Hindu ethics.
Thought processes and mental events are conscious only to the extent they receive illumination from Purusha. In Samkhya, consciousness is compared to light which illuminates the material configurations or ‘shapes’ assumed by the mind. So intellect, after receiving cognitive structures from the mind and illumination from pure consciousness, creates thought structures that appear to be conscious. Ahamkara, the ego or the phenomenal self, appropriates all mental experiences to itself and thus, personalizes the objective activities of mind and intellect by assuming possession of them. But consciousness is itself independent of the thought structures it illuminates.
The nature of the puruṣa–Prakṛti connection is prima facie problematic. How can the inactive soul influence matter, and how could an unintelligent substance, nature, serve anybody’s purpose? Puruṣa is unable to move Prakṛti, but Prakṛti is able to respond topuruṣa’s presence and intentions. Prakṛti, although unconscious, possesses the capability to respond in a specific, structured way because of its sattva guṇa, the information–intelligence aspect of nature. The standard simile in the early Sāṅkhya tradition explains that as milk (an unconscious substance) starts to flow in order to nurture the calf, Prakṛtiflows to nurture puruṣa. In later texts, illumination and reflection are the standard models for this connection (puruṣa is said to illuminate Prakṛti, and Prakṛti reflects the nature of puruṣa), thus solving the problem of how Prakṛti and puruṣa can seemingly borrow eachothers properties without affecting eachothers essential state.
In consequence of Prakṛti’s connection with the soul, Prakṛti evolves many forms: the twenty-three tattva-s (realities) of manifest Prakṛti. The character of this evolution (pariṇāma) is somewhat vague. Is this an account of the origin of the cosmos, or of a single being? The cosmogenic understanding is probably older, and it seems to predominate in later accounts as well. In a pantheistic account the two accounts could be harmonized, but pantheism is alien from classical Sāṅkhya. Īśvarakṛṣṇa is again probably intentionally silent on this conflicting issue, but he seems to be inclined to the microcosmic interpretation: otherwise either a single super-puruṣa’s influence would be needed (that is, God’s influence) to account for how the universe on the whole comes about, or a coordinated effect of all the puruṣa-s together would be required—and there seems to be no foundation for either of these views Sāṅkhya.
The central mechanism of evolution is the complicated interaction of the guṇa-s, which is sensitive to the environment, the substrate or locus of the current process. Just as water in different places behaves differently (on the top of the Himalaya mountain as ice, in a hill creek, in the ocean, or as the juice of a fruit) so do the guṇa-s. In the various manifestations of nature the dominance of the guṇa-s varies—in the highest forms sattvarules, in the lowest tamas covers everything.
The actual order of evolution is as follows: from root-nature first appears intellect (buddhi); from it, ego (ahaṁkāra); from it the eleven powers (indriya) and the five sensibilia (tanmātra); and from the tanmātras the elements (bhūta).
The function of the buddhi (intellect) is specified as adhyavasāya (determination); it can be understood as definite conceptual knowledge. It has eight forms: virtue, knowledge, dispassion and command, and their opposites. So it seems that on the material plane, buddhi is the locus of cognition, emotion, moral judgment and volition. All these may be thought to belong also to consciousness, or the puruṣa. However, on the Sāmkhya account, puruṣa is connected directly only to the intellect, and the latter does all cognitions, mediates all experiences for it. The view of Sāmkhya appears to be that when sattva (quality of goodness, or illumination) predominates in buddhi (the intellect), it can act acceptably for puruṣa, when there is a predominance of tamas, it will be weak and insufficient.
The ego or ahaṁkāra (making the I) is explained as abhimāna—thinking of as [mine]. It delineates that part of the world that we consider to be or to belong to ourselves: mind, body, perhaps family, property, rank… It individuates and identifies parts of Prakṛti: by itself nature is one, continuous and unseparated. It communicates the individuality inherent in the puruṣa-s to the essentially common Prakṛti that comprises the psyche of the individual. So it has a purely cognitive and a material function as well—like so many principles of Sāmkhya.
The eleven powers (indriya) are mind (manas), the senses and the “powers of action” (karmendriya), the biological faculties. The senses (powers of cognition, buddhīndriya) are sight, hearing, smelling, tasting, and touching—they are the abilities, not the physical organs themselves through which they operate. The crude names of the powers of action are speech, hand, foot, anus and lap. They symbolize the fundamental biological abilities to communicate, to take in or consume, to move, to excrete and to generate.
“Manas” (often translated as “mind,” though this may be misleading), designates the lowest, almost vegetative part of the central information-processing structure. Its function is saṁkalpa—arranging (literally ‘fitting together’) or coordinating the indriyas. It functions partly to make a unified picture from sense data, provided by the senses, and partly to translate the commands from the intellect to actual, separate actions of the organs. So, it is both a cognitive power and a power of action. (Later authors take “manas” to also designate the will, for saṁkalpa also has this meaning.)
Intellect, ego, and mind together constitute the antaḥ-karaṇa (internal organ), or the material psyche, while the other indriyas (powers) collectively are called the external organ. The internal organ as an inseparable unit is the principle of life (prāṇa). In cognition, the internal organ’s activity follows upon that of the external, but they are continuously active, so their activity is also simultaneous. The external organ is strictly bound to the present tense, while the psyche is active in the past and future as well (memory, planning, and the grasping of timeless truths).
The material elements are derived from the gross, tamasic aspect of the ego, which yields what Sāmkhya calls tanmātra-s (only-that, that is, unmixed). These in turn yield the elements (bhūta, mahā–bhūta). The elements are ether (ākāśa), air, fire, water and earth. The tanmātra-s seem to be uncompounded sensibilia; perhaps subtle elements or substances, each having only one sensible quality: sound, touch, visibility, taste and smell. The gross elements are probably fixed compounds of the tanmātra-s: ether has only sound, air also touch, fire is also visible, water has in addition taste and earth has all the five qualities.
Human beings are a compound of all these. At death we lose the body made up of the five gross elements; the rest (from intellect down to the tanmātra-s) make up the transmigrating entity, called liṅga or liṅga-śarīra (sign-body), often known in English translations as the “subtle body.” The puruṣa itself does not transmigrate; it only watches. Transmigration is compared to an actor putting on different clothes and taking up many roles; it is determined by the law of (efficient) cause and effect, known also as the law of karma (action).
The world, “from the creator god Brahmā down to a blade of glass” is just a compound of such embodied liṅga-śarīra-s. The gods are of eight kinds; animals are of five kinds – and humans, significantly, belongs to one group only (suggesting an egalitarianism with respect to humans). Of course, the gods of Sāmkhya are not classical Judeo-Christian-Muslim God; they are just extra-long-lived, perhaps very powerful beings within the empirical world, themselves compounds of matter and soul.
Liberation or Moksha
Samkhya regards ignorance (avidyā) as the root cause of suffering and bondage (Samsara). Samkhya states that the way out of this suffering is through knowledge (viveka). Mokṣa (liberation), states Samkhya school, results from knowing the difference between prakṛti (avyakta-vyakta) and puruṣa (jña).
Because Prakṛti is essentially changing, nothing is constant in the material world: everything decays and meets its destruction in the end. Therefore as long as the transmigrating entity persists, the suffering of old age and death is unavoidable.
The only way to fight suffering is to leave the circle of transmigration (saṁsāra) forever. This is the liberation of puruṣa, in Sāṅkhya, normally called kaivalya (isolation). It comes about through loosening the bond between puruṣa and Prakṛti. This bond was originally produced by the curiosity of the soul, and it is extremely strong because the ego identifies ourselves with our empirical state: the body and the more subtle organs, including the material psyche. Although puruṣa is not actually bound by any external force, it is an enchanted observer that cannot take his eyes off from the performance. 
As all cognition is performed by the intellect for the soul, it is also the intellect that can recognize the very subtle distinction between Prakṛti and puruṣa. But first the effect of the ego must be neutralized, and this is done by a special kid of meditational praxis. Step by step, starting from the lowest tattva-s, the material elements, and gradually reaching the intellect itself, the follower of Sāṅkhya must practice as follows: “this constituent is not me; it is not mine; I am not this.” When this has been fully interiorized with regard to all forms of Prakṛti, then arises the absolutely pure knowledge of the metaphysical solitude of puruṣa: it is kevala, (alone), without anything external-material belonging to it.
And as a dancer, after having performed, stops dancing, so does Prakṛti cease to perform for an individual puruṣa when its task is accomplished. She has always acted for thepuruṣa, and as he is no longer interested in her (“I have seen her”), she stops forever (“I have already been seen”)—the given subtle body gets dissolved into the root-Prakṛti. This happens only at death, for the gross body (like a potter’s wheel still turning although no longer impelled) due to causally determined karmic tendencies (saṁskāra-s) goes on to operate for a little while.
Puruṣa enters into liberation, forever. Although puruṣa and Prakṛti are physically as much in contact as before—both seem to be all-pervading in extension—there is no purpose of a new start: puruṣa has experienced all that it wanted.
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