In Jainism, the attainment of liberation (moksha) by a soul is a deeply spiritual event with specific doctrinal signs and descriptions:

1. Destruction of All Karmas: Liberation occurs when a soul has completely eradicated all types of karmas, especially the four destructive (ghātiyā) karmas: deluding, knowledge-obscuring, perception-obscuring, and obstructing karmas.

1. Kevala Jnana (Omniscience): Before liberation, the soul attains Kevala Jnana, or infinite knowledge. A Kevali (omniscient being) is free from all ghātiyā karmas but still has non-destructive (aghātiyā) karmas attached. After these are shed, the soul attains moksha.

1. Physical Signs at Liberation: Jain texts describe that at the moment of liberation, the soul leaves the body and rises straight to the top of the universe (Lokottama loka or Siddhashila), never to return to the cycle of birth and death (samsara).

1. No Return to Samsara: Once a soul is liberated, it never reincarnates or returns to worldly existence.

1. Scriptural Testimony: The knowledge of a soul’s liberation comes primarily from Jain scriptures (Agamas), which narrate the liberation of Tirthankaras and other great souls. For example, Mahavira’s liberation is described in detail in Jain texts.

1. Witnessed by Omniscients: According to Jain tradition, only those who have attained Kevala Jnana (omniscience) can truly know when another soul attains liberation. Ordinary beings rely on scriptural authority.

In summary, in Jainism, we know a soul has attained liberation through scriptural accounts, logical reasoning based on karma theory, and the testimony of omniscient beings, not through ordinary perception or worldly evidence.