Atman is the Hindu word meaning ‘soul’ or ‘spirit’. Atman is the manifestation of Brahman in all living things. Some Hindus find it helpful to think of it as the ‘real person’ trapped inside the physical body.
Atman comes from Brahman, the Ultimate Reality. Hindus believe that atman is eternal and will live on after the body dies, unlike the human mind. The bodies and minds of both humans and animals die, but atman is released at death. Atman can be reincarnated into the body of any living thing, including an animal, a bird or a human, perhaps thousands of times:
As a person puts on new garments, giving up old ones, the soul similarly accepts new material bodies, giving up the old and useless ones.Bhagavad Gita 2.2
The physical body is like clothes for the soul: clothes wear out, like bodies. New clothes – or a new body – can replace old. The soul is permanent (eternal): it never dies or wears out.
In one of the Hindu scriptures, the Upanishads, a boy asks his father,
What is ‘reality’? What is ‘truth’? In response, the father explains the concept of atman using the analogy of putting salt in water:
Throw the water away and then come back to me again.” The son did so; but the salt was not lost, for the salt existed forever. Then the father said, “Here likewise in this body of yours, my son, you do not perceive the True; but there, in fact, it is. In that which is the subtle essence, all that exists has its self (atman). That is the True, that is the atman, and that is what you are.Chandogya Upanishad 6.12
This analogy teaches that just like the dissolved salt remains unseen in the water, atman (or the true self) is invisible but real. Even when the salty water is spilled on the ground, the salt (like atman) goes on existing.
How do Hindus believe atman is different from the human mind?
Hindus believe atman is different from the human mind in the sense that it is eternal, and because it is in every living creature, not just humans.