Mandukya Karika, verse 4.76


यदा न लभते हेतूनुत्तमाधममध्यमान् ।
तदा न जायते चित्तं हेत्वभावे फलं कुतः ॥ ७६ ॥

yadā na labhate hetūnuttamādhamamadhyamān |
tadā na jāyate cittaṃ hetvabhāve phalaṃ kutaḥ || 76 ||

76. When the mind does not find any cause superior, inferior or middling, it becomes free from birth. How can there be an effect without a cause?

Shankara Bhashya (commentary)

The superior cause consists of those Dharmas (i.e., duties of life), wholly virtuous, which are prescribed according to different castes and stages of life, and which when performed without any attachment to the result, enable one to attain to the position of gods, etc. The middling cause consists of those duties, mixed with certain irreligious practices the observance of which enables one to attain to the position of man, etc. The inferior cause consists of those particular tendencies, characterised by irreligious practices alone, which lead one to the position of lower creatures, such as beasts, birds, etc. When the mind realising the essence of Self which is one and without a second and which is free from all (illusory) imaginations, does not find the existence of any of the causes, superior, inferior or middling, all1 imagined through ignorance,—like a man of discrimination not seeing any dirt which a child sees in the sky-then it does not undergo any birth, i.e., it does not objectify itself as god, man or beast, which are the effects of their respective causes (enumerated above). No effect can be produced in the absence of a cause, as sprouts cannot come forth in the absence of the seed.