"Life we look upon as the One Form of Existence, manifesting in what is called Matter; or what, incorrectly separating them, we name Spirit, Soul and Matter in man. Matter is the Vehicle for the manifestation [82] of Soul on this plane of existence, and Soul is the Vehicle on a higher plane for the manifestation of Spirit, and these three are a Trinity synthesized by Life, which pervades them all."
- Blavatsky, H. P., The Secret Doctrine, Vol. I, pp. 79, 80.

The soul, the self are synonymous terms in Oriental literature. The main treatise upon the Soul, its nature, purpose and mode of existence is that most famous of all the Eastern Scriptures, the Bhagavad Gita. Deussen summarizes the teaching as to the Atma, the self or soul, as follows:

"If for our present purpose we hold fast to this distinction of the Brahman as the cosmical principle of the universe, the atman as the psychical, the fundamental thought of the entire Upanishad philosophy may be expressed by the simple equation:

Brahman = Atman

This is to say - the Brahman, the power which presents itself to us materialized in all existing things, which creates, sustains, preserves, and receives back into itself again all worlds, this eternal infinite divine power is identical with the atman, with that which, after stripping off everything external, we discover in ourselves as our real most essential being, our individual self, the soul. This identity of the Brahman and the atman, of God and the soul, is the fundamental thought of the entire doctrine of the Upanishads...

The atman is, as has often already been pointed out, an idea capable of very different interpretations. The word signifies no more than 'the self,' and the question then arises what we regard as our self. Three positions are here possible, according as by the atman is [83] understood (1) the corporeal self, the body; (2) the individual soul, free from the body, which as knowing subject is contrasted with and distinct from the object; or (3) the supreme soul, in which subject and object are no longer distinguished from one another, or which, according to the Indian conception, is the objectless knowing subject."
- Deussen, Paid, M.D., The Religion and Philosophy of India, pp. 39, 94.

An Oriental writer comments as follows:

"All organic beings have a principle of self-determination, to which the name of 'soul' is generally given. In the strict sense of the word, 'soul' belongs to every being that has life in it, and the different souls are fundamentally identical in nature. The differences are due to the physical organizations that obscure and thwart the life of the soul. The nature of the bodies in which the souls are incorporated accounts for their various degrees of obscuration.

Each buddhi, with its grasp of senses and the like, is an isolated organism determined by its past karma, and has its own peculiarly associated ignorance (avidya). The ego is the psychological unity of that stream of conscious experiencing which constitutes what we know as the inner life of an empirical self.

The Empirical Self is the mixture of free spirit and mechanism, of purusha and prakriti... Every ego possesses within the gross material body, which suffers dissolution at death, a subtle body, formed of the psychical apparatus, including the senses."
- Radhakrishnan, S., Indian Philosophy. Vol. II, pp. 279, 283, 284, 285.