Abhyasa Yoga-Bhagavad Gita Chapter 6 [The Science of Self Realization]
Krishna Said > Shaloka: 45
But when the yogi engages himself with sincere endeavor in making further progress, being washed of all contaminations, then ultimately, after many, many births of practice, he attains the supreme goal.
A person born in a particularly righteous, aristocratic or sacred family becomes conscious of his favorable condition for executing yoga practice. With determination, therefore, he begins his unfinished task, and thus he completely cleanses himself of all material contaminations. When he is finally free from all contaminations, he attains the supreme perfection–Krishna consciousness. Krishna consciousness is the perfect stage of being freed of all contaminations. This is confirmed in the Bhagavad-gita:
yesam tv anta-gatam papam jananam punya-karmanam
te dvandva-moha-nirmukta bhajante mam drdha-vratah
“After many, many births of executing pious activities, when one is completely freed from all contaminations, and from all illusory dualities, one then becomes engaged in the transcendental loving service of the Lord.”