Srimad Bhagvata Mahapurana: Book 3: Chapter 26: Verses 1-17
The Lord continued: Now I shall tell you, one by one, the distinctive features of the different categories, by knowing which a man is freed once for all from (the yoke of) the modes of Prakrti. I shall (also) explain to you the nature of Knowledge in the form of Self-Realization, which, by cutting the knot of egotism existing in the heart, leads-the Jiva to final beatitude: so declare the wise. The Purusa is no other than the Spirit, who is beginningless, devoid of attributes, existing beyond Prakrti (Matter), revealed in the heart (of all beings) and self-effulgent, nay, pervaded by whom the universe presents itself to our view. This ail-pervading Purusa accepted of his own free will the unmanifest divine Prakrti, consisting of the three Gunas, that sought him in her playful mood. (Already) abiding in Prakrti, the Purusa fell a prey to her charms, that obscure knowledge, and forgot himself the moment he saw her evolving through her Gunas (Sattva, Rajas and Tamas) progeny of various kinds with forms conforming to either of the three Gunas. By identifying himself with Prakrti, who is other than himself, the Purusa attributes the doership of actions which are being performed by the Gunas of Prakrti to himself. It is this feeling of doership which binds him to actions, although (really speaking) he is a mere witness and therefore a non-doer. And it is this bondage through action which makes him helpless (in the matter of pleasurable and painful experiences), although he is independent (in reality), and subjects him to repeated births and deaths even though he is blissful by nature. The knowers of Truth recognize Prakrti as responsible for the identification of the soul with body, with the senses and mind as well as with the agents (the deities presiding over the senses etc.). As for the experience of pleasure and pain they hold the Purusa (identifying himself with Prakrti) to be responsible, although (as a matter of fact) he is beyond Prakrti. Devahuti said: Kindly also tell me, O Supreme Person, the characteristics of Prakrti and Purusa, the two causes of this universe, which in its gross and subtle forms is nothing but a manifestation of these. The Lord resumed : The wise speak of Pradhana (Primordial Matter) as Prakrti-the Pradhana, which consists of the three Gunas (Sattva, Rajas and Tamas), nay, which is unmanifest and eternal and exists both as cause and effect and which, though undifferentiated (in its causal state) is the source of distinct categories (such as Mahat-tattva and so on). The aggregate of twenty-four categories-viz., the five gross elements, the five subtle elements, the four internal senses, the five senses of perception and the five organs of action-is known to be an evolute of the Pradhana. The gross elements are only five, viz., earth, water, fire, air and ether. The number of the subtle elements too is in My opinion just the same: they are smell, taste, colour, touch and sound. The Indriyas (the senses of perception and the organs of action) are ten in number, viz., the auditory sense, the tactile sense, the sense of sight, the sense of taste, the olfactory sense, the organ of speech, the hands, the feet, the organ of generation and the organ of defecation, which is said to be the tenth. The internal sense is seen to have four aspects in the shape of mind, under-standing, ego and reason. Their distinction lies in their functions which represent their characteristics. The disposition of the conditioned Brahma (Brahma manifested through the Gunas of Prakrti) has been recognized (by the knowers of Truth) as consisting of the twenty-four principles just enumerated by Me and no other, Kala (Time) being the twenty fifth. Some people speak of Kala as a potency (destructive power) of the Purusa (God), which causes fear to the doer (the individual soul) who has come to associate himself with Prakrti and is deluded by egotism (arising out of self-identification with body etc.). As a matter of fact, O daughter of Swayambhuva Manu, the Lord Himself, who activates Prakrti-which is only another name for the equilibrium of the three Gunas (Sattva, Rajas and Tamas), and which (in that state) admits of no particular name or form-is designated as Kala (Time).