SB 3.31.30

bhūtaiḥ pañcabhir ārabdhe
 dehe dehy abudho ’sakṛt
ahaṁ mamety asad-grāhaḥ
 karoti kumatir matim
Synonyms: 
bhūtaiḥ — by material elements; pañcabhiḥ — five; ārabdhe — made; dehe — in the body; dehī — the living entity; abudhaḥ — ignorant; asakṛt — constantly; aham — I; mama — mine; iti — thus; asat — nonpermanent things; grāhaḥ — accepting; karoti — he does; ku-matiḥ — being foolish; matim — thought.
Translation: 
By such ignorance the living entity accepts the material body, which is made of five elements, as himself. With this misunderstanding, he accepts nonpermanent things as his own and increases his ignorance in the darkest region.
Purport: 

The expansion of ignorance is explained in this verse. The first ignorance is to identify one’s material body, which is made of five elements, as the self, and the second is to accept something as one’s own due to a bodily connection. In this way, ignorance expands. The living entity is eternal, but because of his accepting nonpermanent things, misidentifying his interest, he is put into ignorance, and therefore he suffers material pangs.