Devotee: Verse number eighteen: "When the yogi, by practice of yoga, disciplines his mental activities and becomes situated in transcendence, devoid of all material desires, he is said to have attained yoga (BG 6.18)."
Prabhupāda: Yes. To keep the mind in equilibrium. That is yoga perfection. To keep the mind, that how you can do if you, in the material field you cannot keep your mind in equilibrium. That is not possible. Take for example this Bhagavad-gītā. If you read daily four times you'll not get tired. But take any other book, after reading one hour you'll get tired. This chanting, Hare Kṛṣṇa. You chant whole day and night, and dance, you'll never get tired. But take another name. Just after half an hour, finished. It is botheration. You see? Therefore to fix up the mind means to keep your mind in Kṛṣṇa, then finished, all yoga. You are perfect yogi. You haven't got to do anything. Simply fix up your mind. Sa vai manaḥ kṛṣṇa-padāravindayor vacāṁsi vaikuṇṭha (SB 9.4.18)—if you talk, talk of Kṛṣṇa. If you eat, eat of Kṛṣṇa. If you think, think of Kṛṣṇa. If you work, work for Kṛṣṇa. So in this way, this yoga practice will be perfect. Not otherwise. And that is the perfection of yoga. Devoid of all material desires. If you are simply desiring for Kṛṣṇa where is the scope of material desire? Finished, all material desire finished. You haven't got to try for it artificially. "Oh, I shall not see any nice girl. I shall close my eyes." That you cannot do. But if you fix up your mind in Kṛṣṇa consciousness you are dancing with so many beautiful girls. That's all right, as brother and sister there is no question. This is practical perfection of yoga. Artificially you cannot do.