In Sanatan Dharma, the concept of Atman (soul) is central to the understanding of ultimate reality, Brahman. Atman is the individual soul, the eternal essence of each being. It is the part of us that is not subject to birth, death, or change. Brahman, on the other hand, is the ultimate reality, the ground of all being. It is the all-pervading consciousness that underlies the universe.

The relationship between Atman and Brahman is one of identity. Atman is not separate from Brahman; it is a part of Brahman. This is the teaching of non-duality, or Advaita Vedanta, which is one of the main schools of thought in Hinduism.

The Upanishads, the sacred texts of Hinduism, contain many passages that explore the relationship between Atman and Brahman. In the Chandogya Upanishad, for example, a student asks his teacher, "What is that by knowing which everything else is known?" The teacher replies, "That art thou." This means that the individual soul (Atman) is identical with the ultimate reality (Brahman).

The realization of the identity of Atman and Brahman is the goal of spiritual practice in Sanatan Dharma. This realization is called moksha, or liberation. Moksha is the state of being free from the cycle of birth and death, and it is the ultimate goal of all spiritual seekers.

There are many different paths to moksha, but all of them involve the cultivation of self-knowledge. This means that the individual must come to know their true nature, which is Atman. When the individual realizes that they are Atman, they also realize that they are Brahman. This is the state of moksha, or liberation.

The concept of Atman and Brahman is a complex and profound one, and it has been the subject of much philosophical debate over the centuries. However, the basic idea is that the individual soul is not separate from the ultimate reality. This is a liberating and empowering truth, and it is the foundation of all spiritual practice in Sanatan Dharma.