SB 3.28.35

The activities of the mind is acceptance and rejection in the material world. So, so long the mind is materialistic, by force this mind is practiced to accept the meditation of the Supreme Personality of Godhead. But when actually one is elevated to the platform of loving the Supreme Personality of Godhead, the mind is automatically absorbed in the thought of the Lord and he has no other object of thinking except the service of the Lord. This dovetailing of the mind with the desire of the Supreme Personality of God..., Godhead is called nirvana, or making the mind one with the Supreme Lord. The…, the best example is certainly Bhagavad-gita, that in the beginning the mind of Arjuna was different from the mind of Krsna. Krsna's mind was that Arjuna should fight, but Arjuna's mind was that he should not fight. So there…, there was disagreement. But after understanding the Bhagavad-gita from the Supreme Personality of Godhead, he dovetailed his mind with the desire of the Supreme Personality of Godhead. This is called oneness. Not that by making this oneness of mind of Arjuna with Krsna the Arjuna and Krsna lost their individuality. The Mayavadi philosophers, they cannot understand this. They think that oneness means the individuality is lost. But actually we find from the Bhagavad-gita that the individuality is not lost, the individual is there. Similarly, when the mind being purified completely in love of Godhead, it is practically my mind becomes the mind of the Supreme Personality of Godhead because my mind at that time does not act separately without being inspired to fulfill the desire of the Lord. A individual soul or the liberated soul has no other activity.

Explanation given here, pratinivrtta-guna-pravahaḥ (p-r-a-t-i-n-i-v-r-i-t-t-a g-u-n-a p-r-a-v-a-h-a-h): pratinivrtta-guna-pravahaḥ. That actually the oneness of the devotee's mind with the mind of the Supreme Personality means that in the conditional stage the mind is always engaged in the activities impelled by the three qualities of this material world. But in transcendental stage, the qualities of the material world cannot disturb the mind of the devotee. He has no other business than to execute the desire of the Lord. That is the highest stage of perfection or nirvana which is called nirvana-mukti, to make the mind completely free from material desires. And the example given here, yatharciḥ. The yatharciḥ, arciḥ means the flame. When the lamp is broken or the oil is finished, we find that the flame of the lamp is extinguished. But according to scientific understanding, the nothing is extinguished, the flame is not extinguished; it is conserved, conservation of energy. Similarly, when the mind stops functioning materially, it means it is conserved in the actions of the Supreme Lord. So the Mayavadi philosophers' conception of ceasing the function of the mind is explained here that…, that cessation of the function of the mind means cessation of the activities under the influence of the three qualities of material nature.