The history of Hindu Philosophy goes back to the earliest times, since when alongside systems of ritual and soteriologies using yoga and meditation, elaborate and often highly sophisticated doctrinal schemes and metaphysical speculation developed within Hinduism. The term `philosophy` has often been used to describe these systems. While there are undoubted similarities between traditional Hindu thinking and modern western philosophy, what traditional Hindu thinkers do would only be partially recognized in contemporary departments of philosophy in western universities. Alternatively, while the term `theology` conveys not only the systematic and transcendent aspects of Hindu thought, but also emphasize its exegetical nature; some schools are atheistic and not concerned with the `theos`. While the flowering of Hindu philosophy and theology occurs between the seventh and seventeenth centuries CE, the origins of philosophical speculation go back to the Veda.

Hindu philosophy is classified into six schools of thought, known as darshanas. Samkhya philosophy is a strongly dualist theoretical exposition of mind and matter, Yoga philosophy is the second form of school, emphasizing meditation closely based on Samkhya. Nyaya philosophy or logics and Vaisheshika, an empiricist school of atomism relate to Hindu philosophy. Mimamsa is an anti-ascetic and anti-mysticist school of orthopraxy, while Vedanta, opposes Vedic ritualism in favour of mysticism. The most notable feature of Indian theology and philosophy is that it is expressed primarily through commentaries and sub-commentaries on sacred texts. Although there are some independent philosophical texts apart from the terse Sutra literature which stands at the beginning of a commentarial tradition, the traditions are primarily exegetical. Sutras are short condensed aphorisms which summarize the teachings of a school. These are often coupled together into three groups, namely Samkhya-Yoga, Nyaya-Vaishesika, and Mimamsa-Vedanta, for both historical and conceptual reasons: Samkhya is the theoretical substrate of Classical Yoga; Vedanta is a continuation of Mimamsa; and Nyaya, logic, is used in the metaphysical speculations of Vaishesika.

In the history of Hindu philosophy, the distinction of these six philosophical schools existed in the Gupta period `golden age` of Hinduism. With the disappearance of Vaisheshika and Mimamsa, it was archaic by the later middle ages. Eventually the various sub-schools of Vedanta, like the Dvaita `dualism`, Advaita `non-dualism` and others came to prominence as the main partition of religious philosophy. Nyaya survived into the 17th century as Navya Nyaya `Neo-Nyaya`, however Sankhya gradually lost its status as an independent school and its doctrine absorbed into Yoga and Vedanta.

As Hindu philosophy Samkhya system is reckoned as the oldest systematic philosophy to have emerged in the Hindu tradition and is enormously influential on later theological schools, especially tantric Shaivism and the Paricaratra. Samkhya proposes that everything in reality is derived from purusha and prakriti. There are many living beings and they possess consciousness. Prakriti is made up of three dispositions known as qualities like activity (rajas), inactivity (tamas) and steadiness (sattva) that arise when the two other gunas are held in equilibrium. Indeed, other schools of Indian thought, such as Nyaya and Vedanta, developed during the early centuries of the common era partly due to polemical reactions to Samkhya philosophy. The term samkhya, which means `enumeration` or `calculation`, has two senses: one a general sense used in renounced traditions, including Jainism and Buddhism, to denote the enumeration and categorization of elements which comprise the cosmos; the other a more specific sense to refer to the Samkhya philosophical system which developed a tradition of commentaries upon its key texts and is the backdrop to Yoga.

In Hindu philosophy, Yoga is the name of one of the six orthodox philosophical schools and the Yoga philosophical system is intimately associated with the Samkhya School. The Yoga school as explained by Patanjali concept, it is related to the Samkhya psychology and metaphysics, but is more theistic than the Samkhya. The Nyaya School is based on the Nyaya Sutras and was written by Aksapada Gautama. The most important contribution made by this school is its methodology. This methodology is based on a system of logic that has subsequently been adopted by the majority of the Indian schools. This belief said that one can only obtain valid knowledge from suffering, and they took great pains to identify valid sources of knowledge and distinguish these from mere false opinions.

Apart from these, there are striking parallels between the later Samkhya philosophy, medical systems or Ayurveda, and Buddhist systems, particularly the Abhidharma and Yogacara Buddhism. Prakrti, a wider concept than the western category `matter`, which includes the western idea of the `mind`, evolves or transforms from an unmanifested state into a manifested state, through a series of stages or levels in which different categories appear. These categories, or tattvas (literally, `hat-ness`) comprise the universe of experience. This evolution or transformation (parindma) is governed, or kept in balance, by three qualities (guna), namely the qualities of light (sattva), of passion or energy (rajas) and of darkness or inertia (tamas). These qualities are very important in Hindu thought and later become the basis for a number of associations and classifications. For example the top three classes are associated with the gunas, as are categories of food into `cool` (sattva), `hot` (rajas) and `dulling` (tamas). While the self (purusa) appears to be entangled m matter and appears to transmigrate in a subtle body, it is only the empirical self under the sway of the gunas which does this.

As per the Samkhya enumeration of the principles of experience into twenty-five categories is that the structure refers both to individual psycho-physiology and to cosmological categories. The evolution of matter is both a cosmic and an individual process; both physiological functions and the constituents of the physical world emerge from the sense of ego. The first transformation from matter is translated as the `intellect` or `higher mind` (buddhi), also called `the great one` (mahat), and refers to both an individual`s psychological functioning and to a higher level in a hierarchical cosmology. From buddhi the sense of ego (ahamkara) develops, from which emerges the mind (manas), the five senses and their objects, the five organs of action or motor functioning, five subtle, and five gross elements.

Kanada founded the Vaisheshika School of Hindu philosophy and it declares an atomic pluralism. All objects in the physical universe are bound to reduce to certain types of atoms, and Brahman is regarded as the fundamental force that causes consciousness in these atoms. The prime objective of the Purva Mimamsa School in Hindu philosophy was to establish the authority of the Vedas. Consequently, this school formulated the rules of Vedic interpretation.

The Hindu philosophy includes the thoughts of the Upanisads that are referred to as the Vedanta, the `end of the Veda`. This is a term which is also used for the theological tradition developing from them. This immensely rich tradition is so influential that, at a popular level in the West, `Vedanta` is taken to be Indian philosophy par excellence. The Vedanta tradition is, however, divided into two main developments which are both referred to as schools of exegesis or enquiry (mimamsa). These are the Purva Mimamsa, sometimes simply called Mimamsa, and the Uttara Mimamsa, sometimes simply called Vedanta. While the former is concerned with correct action in accordance with dharma, the latter is concerned with correct knowledge (jnana) of brahman. The Mimamsa accepted the logical and philosophical teachings of the other schools and they believed that only by acting in harmony with the instructions of the Vedas could one attain salvation. The Mimamsa School later shifted its views and began to teach the doctrines of Brahman and freedom. Vedanta, or later Mimamsa School, concentrates on the philosophical teachings of the Upanishads rather than the ritualistic commands of the Brahmanas.

Advaita is probably the most recognized of all Vedanta schools of Hindu philosophy. Advaita literally means `non duality` and its first great consolidator was Adi Shankaracharya. By analysing the three states of experience - waking, dreaming, and deep sleep, he established the singular reality of Brahman. Nimbarka, a 13th century Vaishnava Philosopher from the Andhra Pradesh, proposed Dvaitadvaita thoughts in Hindu philosophy. Three categories of existence, namely Brahman, soul, and matter are followed by this school of thought. Shuddhadvaita by Vallabhacharya and Achintya Bheda Abheda by Chaitanya Mahaprabhu were the important thoughts of Hindu philosophy in later ages.

The most influential school of theology in India has been the Vedanta, exerting enormous influence on all religious traditions and becoming the central ideology of the Hindu Renaissance in the nineteenth century. It has become the philosophical paradigm of Hinduism par excellence. As has been noted, the term `Vedanta` refers to the Upanisads and their teachings as well as to the traditions inspired by them, which follow from them. At the head of these traditions are Sutras, intended for memorization, which summarize the teachings of the Veda and Upanisads. A number of schools develop within the Vedanta tradition, whose founders and chief exponents write commentaries on the Brahma Sutra, thereby establishing an independent school (sampraddya) of interpretation. Other texts were also the subject of exegetical commentary, most notably the early Upanisads and the Bhagavad Gita. This group of texts the Brahma Sutra, the Upanisads and the Gita - forms the `triple basis` of Vedanta commentarial tradition. The most important Vedanta traditions are Advaita (`Non-Dualist`) Vedanta, Visistadvaita (`Qualified Non-Dualist`) Vedanta and Dvaita (`Dualist`) Vedanta.

Hindu philosophy with its entire reality, spirituality, theories of creation is one of the colossal and unlimited areas of cultivation and research for the Indian scholars. The different schools of thoughts still prevail in different sects of the nation.