Srimad Bhagavatam Canto 11, Chapter 10, Text 09

SB 11.10.9

nirodhotpatty-anu-brhan-
 nanatvam tat-krtan gunan
antah pravista adhatta
 evam deha-gunan parah
 
Translation: 
 
Just as fire may appear differently as dormant, manifest, weak, brilliant and so on, according to the condition of the fuel, similarly, the spirit soul enters a material body and accepts particular bodily characteristics.
 
Purport: 
 
Although fire may appear and disappear within a particular object, the element fire always exists. Similarly, the eternal soul appears within a suitable body and then disappears from that body, but the soul always exists. Just as fire is different from its fuel, the soul is different from the body. A match makes a tiny fire, whereas the explosion of a huge gasoline tank will send flames shooting up into the sky. But still, fire is one. Similarly, one spirit soul may appear in the body of Brahma and another in the body of an ant, but the spirit soul is qualitatively the same in every body. Because of ignorance we impose the bodily characteristics upon the soul, and thus we say that a particular person is American, Russian, Chinese, African or Mexican or that he is old or young. Although such designations certainly apply to the body, they do not apply to the spirit soul, which is described here as parah, or a transcendental entity. As long as the bewildered spirit soul remains inimical to the Supreme Personality of Godhead, the designations of the gross and subtle bodies will wrap themselves around him, keeping him in darkness. If one intellectually identifies oneself with various materialistic philosophies of life, he becomes covered by the subtle mind. Ultimately everything that exists is part and parcel of the Absolute Truth, Lord Krsna. When the living entity realizes this, he becomes nirupadhi, or free from material designations. This is his constitutional position.
Srimad Bhagavatam Canto 11, Chapter 10, Text 08
Srimad Bhagavatam Canto 11, Chapter 10, Text 10