Srimad Bhagavatam Canto 06, Chapter 16, Text 57

SB 6.16.57

yad etad vismrtam pumso
 mad-bhavam bhinnam atmanah
tatah samsara etasya
 dehad deho mrter mrtih
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
When a living entity, thinking himself different from Me, forgets his spiritual identity of qualitative oneness with Me in eternity, knowledge and bliss, his material, conditional life begins. In other words, instead of identifying his interest with Mine, he becomes interested in his bodily expansions like his wife, children and material possessions. In this way, by the influence of his actions, one body comes from another, and after one death, another death takes place.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada: 
Generally the Mayavadi philosophers or persons influenced by Mayavadi philosophers think themselves as good as the Supreme Personality of Godhead. This is the cause of their conditional life. As stated by the Vaisnava poet Jagadananda Pandita in his Prema-vivarta:
krsna-bahirmukha haña bhoga vañcha kare
 nikata-stha maya tare japatiya dhare
As soon as a living entity forgets his constitutional position and endeavors to become one with the Supreme, his conditional life begins. The conception that the Supreme Brahman and the living entity are equal not only in quality but also in quantity is the cause of conditional life. If one forgets the difference between the Supreme Lord and the living entity, his conditional life begins. Conditional life means giving up one body to accept another and undergoing death to accept death again. The Mayavadi philosopher teaches the philosophy of tat tvam asi, saying, “You are the same as God.” He forgets that tat tvam asi applies in terms of the marginal position of the living entity, who is like sunshine. There is heat and light in the sun, and there is heat and light in the sunshine, and thus they are qualitatively one. But one should not forget that the sunshine rests on the sun. As the Lord says in Bhagavad-gita, brahmano hi pratisthaham: “I am the original source of Brahman.” The sunshine is important because of the presence of the sun globe. It is not that the sun globe is important because of the all-pervasiveness of the sunshine. Forgetfulness and misunderstanding of this fact is called maya. Because of forgetfulness of one’s constitutional position and that of the Supreme Lord, one comes into maya, or samsara — conditional life. In this regard, Madhvacarya says:
sarva-bhinnam paratmanam
 vismaran samsared iha
abhinnam samsmaran yati
 tamo nasty atra samsayah
When one thinks that the living entity is nondifferent in all respects from the Supreme Lord, there is no doubt that he is in ignorance (tamah).
Srimad Bhagavatam Canto 06, Chapter 16, Text 56
Srimad Bhagavatam Canto 06, Chapter 16, Text 58