Two birds, bound together in a close friendship, perch on the same tree. One of them eats the sweet fruit with great pleasure, while the other just looks on.
This verse from the third chapter of the Mundaka Upanishad succinctly describes the "Tree of Samsara," which resembles a banyan tree with its roots above in the sky and branches spreading broadly downward. According to Shankaracharya, this tree is supported by maya, or ignorance, and on its branches hang the fruits of the actions of living beings. The tree is a metaphor for the body which has its roots above in Brahman (the Self) and its sense organs below buried beneath the ground. The jiva identifies with the body (tree), and experiences the fruits of his or her actions as either pleasant (sweet) or painful (bitter). The bird's inseparable companion represents pure awareness acting as the witness.
Seated on the same tree, the jiva, deluded by his ignorance, grieves of his powerlessness. But when he learns of the Self, becomes free of his misery.
Due to the jiva's attachment to the world, he becomes deluded and feels powerless to his insatiable likes and dislikes and the fact that life is a zero-sum—for every sweet fruit, there's a bitter one. He eventually longs for freedom and seeks a way out of his predicament. After some time spent purifying his actions and practicing various spiritual disciplines, he seeks out a teacher, learns Vedanta and fixes his mind on the Self. It's this knowledge and meditation on the Self that finally frees the jiva from the binds of samsara.
The word jiva signifies any living being including animals, plants, micro organisms and beings still unknown, but in scripture usually refers to the individual. The human jiva is defined as awareness plus a body-mind-sense complex. Awareness is atma (the Self embodied), while the body-mind-sense complex is combination of the gross body, subtle body and causal body. Briefly, the gross body represents the physical body with its elements, components and physiological functions; the subtle body is the mind-intellect-ego; and the causal or "seed" body is the subconscious.
Jiva is also defined by its three states of experience: waking, deep sleep and dreaming. Traditionally, it’s shown that each of these states is of the nature to change. In order to enter the deep sleep state, the waking state must end; and in order to enter the dream state, the deep sleep state must end. Furthermore, the "me" I believe myself to be isn't even present in every state. For example, while in deep sleep. Erroneously, the jiva identifies as the waker. But Vedanta shows using logic that the waking state, is no more real than the other two.
The waker is said to be a consumer of experience or "the one with thirteen mouths.” This includes the ten senses (five sense instruments and five sense organs) plus the mind, intellect and ego. Vedanta teacher James Swartz describes the senses as aggressively seeking experience, while the physical body consumes matter, the mind chews emotion, the intellect eats ideas, and the ego “gobbles any experience it believes will make it feel adequate and happy."
However, the three states of experience don’t provide the entire picture. There is a fourth, and yet, it is not a state because it's that which never changes and is always present. It is the Self, our true identity and substrate of all three states.
With each of the aforementioned examples, Vedanta attempts to show us how the jiva misidentifies with the body, mind or experience. Another way to look at the jiva is as an object with multiple sheaths concealing its true identity. The further down we go, the more subtle the sheaths become. If we imagine the jiva to be an onion, the outer sheath is the gross sheath (the body), followed by the energy sheath (the physiology), mind sheath, intellect sheath and finally, the bliss sheath (the subconscious). Vedanta shows that none of these sheaths which I identify with can be me because they are all objects known by me.
Lastly, the jiva is sometimes described as a mirror with three parts: (1) light shining as pure, original consciousness (2) a reflecting medium (the mirror) and (3) the reflection. The reflecting medium is represented by the three bodies—gross, subtle, and causal. However, the reflecting medium is small and impure due to the gunas (maya). As a result of an imperfect medium, the jiva identifies with the distorted reflection instead of the original pure light.
Why is the jiva so easily confused about his identity? Because the jiva is a mixture of Self and not-Self; spirit and flesh. The confusion also comes from the one original consciousness appearing as many separate individuals. What appears as billions of individuals is really just the five basic elements plus awareness (albeit, each conditioned by ignorance, formed tendencies and the gunas).
There are three theories regarding the nature of the eternal Jiva (with a capital "J," signifying the archetype or universal, not the personal):
Jiva forgets its nature due to pure consciousness being limited by the upadhi of the intellect sheath. An upadhi is something added to an object that changes its appearance due to its proximity. For example, if I pour water into a red bottle, the water will appear red. In this case, the bottle is the upadhi and the jiva believes the water to be red.
Jiva forgets its nature due to original consciousness taking on the qualities of the reflecting medium. The jiva believes it is the distorted reflection caused by the dull reflecting medium instead of the pure light.
Jiva is like a character under a spell. Pure consciousness under the influence of maya believes it has become a man or woman.
According to karma theory, the jiva is stuck in a cycle of rebirth (samsara). What keeps the jiva in this rebirth loop is their binding likes and dislikes and the belief they are the doer/enjoyer. The result is accrued karma which propels them into another rebirth where they are given another chance to realize the truth and exhaust their karma. The premise is that eventually the jiva recognizes the limitations of samsara, purifies their actions, and gains the knowledge that unifies them with the Self and frees them. Ironically, the jiva was always free and unified with the Self but just didn't know it.
In the end, it’s only the jiva's ignorance about its true identity that keeps it in samsara. Thus, “jiva” is not a permanent state but rather, a status. According to Vedanta, all individuals will eventually change their status from jiva to jivanmukta (a Self-actualized individual liberated from all future births). The difference between jiva and jivanmukta is one still identifies with the doer/enjoyer, while the other identifies with the Self; one suffers due to their perceived limitations, while the other enjoys limitless freedom as pure, eternal awareness.