In the context of the Indian civilization Yoga is a path to Moksha, or Self realization. Moksha is itself one of the four aims of life, along with Dharma/Virtue, Artha/Prosperity and Kama/Enjoyment.
THE FOUR AIMS OF LIFE
The Purusharthas, or ‘The four aims of Life’ is the over arching organizational scheme in Indic thought. There are teachings and texts for each of the four aims, such as the Arthashastra, a voluminous text on statecraft and worldly wisdom, the Kama Sutra, Dharmashastras like the great epics Ramayana and Mahabharata, and Mokshasashtras like the Yoga Sutra. Depending on aptitude, individuals may be strongly inclined towards one or more of the aims at different times in their lives. Individuality is key here as not all humans will take the same path, and this makes for the great diversity seen in India within the worldly and spiritual spheres.
The theme of Yoga and self-realization is found in the earliest Indic texts, the Vedas and Upanishads and this becomes codified as the Yoga Sutra about 2000 years ago, giving a well defined path and practices. Other, related paths were also developed and codified over this time, like Buddhism, Jainism, and later Tantra.
In the Bhagavad Gita different types of Yoga are mentioned, such as Karma Yoga (service), Bhakti Yoga (devotion) and Janana Yoga (knowledge), once again giving individuals a choice according to their aptitude.
The Yoga Sutra of Patanjali contains an 8-fold path, beginning with ethical considerations for the aspirant, and describes a stepwise praxis leading to meditation. This text does not list postures other than the seated meditation pose and the mention of postures familiar today occurs in later Yoga texts as an assistance to the practise of meditation.
THE LIMITS OF THOUGHT
The Yoga Sutra begins with “The aim of Yoga is to still and thereby transcend thought.”
The Mundaka Upanishad, centuries before the Yoga Sutra gives a very good understanding of why this would be stated in saying “Self knowledge is of two kinds, historical and timeless. And thought cannot reach the timeless.” Therefore, Yoga/Meditation.
Thought in trying to derive ultimate self- knowledge seeks through constructing cause- effect chains the absolute beginning of the world, of which the individual is a part. Without knowing how it all began one’s self knowledge remains partial. But thought cannot reach what it frames as the first cause, its attempts being similar to chasing the horizon and which can
never be reached. Therefore the transcending of thought is desired because it is too limited an approach to self-knowledge. In this regard, the physicist David Bohm once asked, “If thought is only part of the whole, can it ever contain the whole?”
In the Yoga tradition consciousness is understood as the deepest aspect of reality, on which all sensory and cognitive phenomena depend, including the body. If consciousness were merely an historically arisen attribute of matter then the exploration of consciousness could not lead to an ultimate knowledge as the Yoga tradition asserts.
The Yoga tradition is opposed to the philosophy of Materialism, and Theism, both of which do take seriously the idea of ‘the first cause’, the former mathematizing it as ‘the big bang’ and the latter anthropomorphizing as ‘God’. The idea of God found in traditional Western theology, as the Creator apart from its creation does not exist in the Indian approach. In fact, the text ‘Yoga Vasistha’ says “If this God is truly the ordainer of everything in this world, of what meaning is any action?”. Due to this, there is nowadays academic criticism of using the words ‘Religion’ and ‘God’ in talking about what in India is called ‘Dharma’. Dharma is not the same as Religion.
TWO KINDS OF KNOWLEDGE
Dharmic epistemology sees two kinds of knowledge, Gyana and Vigyana. Vigyana is akin to Science, the method of measurement, thought and since it relies upon causality but invariably gets stuck at the 'first cause' it is understood as useful but limited.
While Vigyana is divided or dualistic knowledge, Gyana is non-dual knowledge, transcendent of measurement and thought and this is the goal of meditation in Yoga.
It is easy to see that thought encounters immeasurability when it reaches for the first cause. The Upanishads say that three things are beyond measure, Atma/Self, Jnana/ Consciousness and Brahman/Totality. These are all beyond measure because they are not external objects, they are all self. One cannot step outside of oneself, nor awareness, nor the totality. Knowledge of what is beyond measure can only be in the form of self-knowledge.
Meditative states if deep enough, give rise to a visionary self knowledge that Yoga points to, and the Chandodya Upanishad speaks of as “Tat Tvam Asi”, meaning “This is you.” You are the universe looking at itself.
"The Indian term yoga is derived from the Sanskrit verbal root yuj, 'to link, join, or unite,' which is related etymologically to 'yoke,' a yoke of oxen, and is in sense analogous to the word 'religion' (Latin re-ligio), 'to link back, or bind.' Man, the creature, is by religion bound back to God. However, religion, religio, refers to a linking historically conditioned by way of a covenant, sacrament, or Quran, whereas yoga is the psychological linking of the mind to that superordinated principle 'by which the mind knows.' Furthermore, in yoga what is linked is finally the self to itself, consciousness to consciousness; for what had seemed, through māyā, to be two are in reality not so; whereas in religion what are linked are God and man, which are not the same.”
Joseph Cambell, The Masks of God, Vol III: Oriental Mythology