Vichara
Vichāra means deliberation; It is the faculty of discrimination that discerns the Real, Brahman, from the unreal. Etymology. "Vichāra" () means deliberation; its root is वि (prefix to verbs and nouns it expresses) – चर् (to move, roam, obtain knowledge of). It is the faculty of discrimination between right and wrong; it is deliberation about cause and effect, and the final analysis. This Sanskrit word, "Vichāra", does not have a corresponding word in English. Textual references. Aitareya Aranyaka (II.iii.2.5) of the Rig Veda tells us that in man alone is the "Atman" ('Self') most manifest, for man is best endowed with  intelligence and discrimination, and who knowing the higher and the lower worlds aspires to achieve immortality through mental things. Taittiriya Upanishad tells us:- that all should know Brahman as existing in the intellect in which, Shankara explains, are hidden – a) 'knowledge', b) 'the knowable' and c) 'the knower', as also enjoyment and liberation. The relationship between the Individual self and the Universal Self reveals the actual source of thought and action; it reveals Brahman; "vichāra" (reflection and contemplation) results in disinterest in that which is not the source of anything in this world. Vedanta ( the eternal path) activates "vichāra" ('inquiry ') to increase " viveka " ('discrimination') to deconstruct " vivarta " ('false superimposition') to destroy " vasanas " ('root desires') and thus establish " vairagya " ('detachment'), become a " vidvan " ('wise person') and attain " vijnana " ('self-realization'); these factors combined facilitate in the human aspiration and Divine Dispensation working harmoniously together. "Vichāra" is "Atma-vichāra" in Advaita Vedanta, but Samkhya is more concerned with "Tattva-vichāra", about the nature of the tattvas. Interpretation. "Vichāra" is reflection and contemplation upon the meaning of Vedantic truths, and leads the individual to true knowledge, it leads to Brahman, the Universal Self. It is also the enquiry into the nature of the  Atman, Satya, Ishvara and Brahman. Vedanta. "Vichāra" or discriminating reasoning is one of the five "Vedanta" methods for awakening spiritual consciousness. Contrary to faith, which is concerned primarily with the essence of a thing and not merely with its appearance; reason, which begins with doubt, relies on appearance of things and not on their essential nature. There are three types of reasoning – "vada" or academic reasoning, "jalpa" or reasoning in a dogmatic and negative way whether rationally or irrationally, and "vitanda" or reasoning that seeks only to lay bare defects of or confuse the opponents. In "Vedanta", rational reasoning is  vichāra that discriminates between the real and the unreal; it dispels prejudices such as irrational doubts, preconceived notions/ideas and personal sentiments to scrutinize the meaning of Truth. Shankara in his commentary on the Mandukya Upanishad explains that Vedantic reasoning reveals the essential meaning of scriptural statement in the context of its goal, proves the logical untenability of all contrary concepts so as to establish the intelligibility of non-dualism and expose the mutually contradictory nature of dualistic views about Reality. The process of Vedantic reasoning is three-fold viz; through " shravana ", " manana " and "nididhyasana", with the aspirant, endowed with   shraddha , reasoning with an open mind. Atma-vichara. "Vichara", Self-inquiry, also called "jnana-vichara" or "" by devotees of Ramana Maharshi, is the constant attention to the inner awareness of 'I' or 'I am'. It was recommended by Ramana Maharshi as the most efficient and direct way of discovering the unreality of the ‘I'-thought, and then discovering one's identity with its source. According to David Frawley, "atma-vichara" is the most important practice in the Advaita Vedanta tradition, predating its popularisation by Ramana Maharshi. It is part of the eighth limb of Patanjali's Yoga Sutras, which describes the  various stages of samadhi. Meditation on "I-am-ness" is a subtle object of meditation. It is also described in the "Yoga Vasistha", a syncretic work which may date from the 6th or 7th century CE, and shows influences from Yoga, Samkhya, Saiva Siddhanta and Mahayana Buddhism, especially Yogacara. Ramana taught that the 'I'-thought will disappear and only "I-I" or Self-awareness remains. This results in an "effortless awareness of being", and by staying with it this "I-I" gradually destroys the vasanas "which cause the 'I'-thought to rise," and finally the 'I'-thought never rises again, which is Self -realization or liberation. Meditation. "Samprajnata Samadhi", also called "savikalpa samadhi" and "Sabija Samadhi", is meditation with support of an object. "Samprajata samadhi" is associated with deliberation, reflection, bliss, and I-am-ness. Deliberation and reflection form the basis of the various types of "samapatti":