CC Ādi 7.123
dehe ātma-buddhi — ei vivartera sthāna
The jīva, or living entity, is a spiritual spark who is part of the Supreme Personality of Godhead. Unfortunately, he thinks the body to be the self, and that misunderstanding is called vivarta, or acceptance of untruth to be truth. The body is not the self, but animals and foolish people think that it is. Vivarta (illusion) does not, however, denote a change in the identity of the spirit soul; it is the misconception that the body is the self that is an illusion. Similarly, the Supreme Personality of Godhead does not change when His external energy, consisting of the eight gross and subtle material elements listed in the Bhagavad-gītā (bhūmir āpo ’nalo vāyuḥ, etc.), acts and reacts in different phases.