Experience of diversity [form] becomes oneness in deep sleep and Oneness [formless] becomes diversity in waking or dream. Therefore, that which becomes diversity [form], and that which becomes Oneness [formless] is not our physical entity, because the physical entity is present only in waking and dream. The one, which is aware of all the three states, is formless, apart and eternal which is the soul. The soul/spirit itself is ultimate truth/Christ/Brahman/Buddha.