To understand the concept of Aatma, a poem was written in the Rig Veda, about 8500 years ago.

There exist two birds, seated on a branch on a tree. One satiates itself by eating a fruit, while the other watches the previous eating the said fruit.

This is a metaphor. The bird that is eating the said fruit is referencing one's body, that partakes in the intricacies of life, and uses its sense organs to enjoy every aspect of this life, while the bird watching the other is one's Aatma.

There are three levels to this philosophy.

One states that "I am observing you".

The other states that my Mann, bird 2 (mind) watches over my Shareer, bird 1 (body). In other words, "I am observing myself".

The third questions, "What entity watches over my mind?"

So the third level states that my Aatma (consciousness) watches over my Mann (mind), or "I am observing my own mind". In English, we may refer to it as recursion. This ability exists only in humans. This trait of observing oneself, as a witness, without getting emotionally involved, stems from the existence of Aatma.

Rig Veda, along with Upanishads, also state that humans that search for Artha (meaning) to one's life, is moving towards Aatma-gyan (self-realization).