Prabhupāda: A mantra should be captured from the disciplic succession. According to Vedic injunction, sampradāya-vihīnā ye mantrās te nisphala mataḥ (Padma Purāṇa): "If the mantra does not come through disciplic succession, then it will not be active." Viphala. Mantrās te viphalāḥ. Viphala means "will not produce result." Mantrās te viphalāḥ mataḥ. So mantra has to be received through the channel; then it will act. Mantra cannot be manufactured. Mantra must be from the original Supreme Absolute, coming down through disciplic succession, channel. It has to be captured in that way, and then it will act. Sampradāya-vihīnā ye mantrās te nisphala mataḥ.
So according to our Vaiṣṇava sampradāya, the mantra is coming down through four channels. One is coming through Lord Śiva, one is coming through Goddess Lakṣmī. Not one; different . . . one thing is coming in different channel. One through the channel of Brahmā, one through the channel of Lord Śiva, one through the channel of Lakṣmī and one through the channel of Kumāras. So they are called four sampradāya. So one has to take mantra, either of these four sampradāya. Then that mantra is active, and if we perform that mantra in that way, it will act. Sampradāya-vihīnā ye. And if one does not receive this mantra in either of these sampradāya, channel, then viphala, it will not act; it will not give fruit.
Yoko Ono: If the mantra itself has such power, does it matter where you receive it, where you take it?
Prabhupāda: Yes. Yes. That is a fact. The example is given, just like milk. Milk is nutritious. That's a fact. Everyone knows. But if the milk is touched through the tongue of a serpent, it is no more nutritious, it is poison.