Transmigration among the 8,400,000 species is due to the mind's being polluted by certain material qualities. Due to the mind, the soul is subjected to pious and impious activities. The continuation of material existence is like the waves of material nature. In this regard. Śrīla Bhaktivinoda Ṭhākura says, māyāra vaśe, yāccha bhese', khāccha hābuḍubu, bhāi: "My dear brother, the spirit soul is completely under the control of māyā, and you are being carried away by its waves." This is also confirmed in Bhagavad-gītā:
- prakṛteḥ kriyamāṇāni
- guṇaiḥ karmāṇi sarvaśaḥ
- kartāham iti manyate
"The bewildered spirit soul, under the influence of the three modes of material nature, thinks himself the doer of activities, which are in actuality carried out by nature." (BG 3.27)
Material existence means being fully controlled by material nature. The mind is the center for accepting the dictations of material nature. In this way the living entity is carried away in different types of bodies continuously, millennium after millennium.
- kṛṣṇa bhuli' sei jīva anādi-bahirmukha
- ataeva māyā tāre deya saṁsāra-duḥkha
- (Caitanya-caritāmṛta, Madhya 20.117)
Due to the living entity's forgetfulness of Kṛṣṇa, one is bound by the laws of material nature.