Prabhupada's lecture - Śrīmad-Bhāgavatam 1.8.39 - Los Angeles, May 1, 1973
So Kṛṣṇa can be felt, Kṛṣṇa can be present more acutely in separation. That is Caitanya Mahāprabhu's teaching: to love Kṛṣṇa in separation. Just like Caitanya Mahāprabhu in separation: govinda-viraheṇa me. Śūnyāyitaṁ jagat sarvaṁ govinda-viraheṇa me. He was thinking that "Everything is vacant without Govinda, without Kṛṣṇa." So everything is vacant, but Kṛṣṇa consciousness is there. Kṛṣṇa consciousness is there. That is the highest perfectional... When we'll see everything is nothing, simply Kṛṣṇa consciousness is there, that is the highest. That is the gopīs.
Therefore gopīs are so exalted. Not for a single moment they could forget Kṛṣṇa. Not for a single moment. Kṛṣṇa was going in the forest with His cows and calves, and gopīs at home, they were disturbed in the mind, "Oh, Kṛṣṇa is walking bare-footed. There are so many stones and nails. There is pricking Kṛṣṇa's lotus feet, which is so soft that we think our breast as hard when Kṛṣṇa puts His lotus feet. Still He's walking." They are absorbed in this thought. And they are crying. So they are so anxious to see Kṛṣṇa back home in the evening that they are standing on the way, on the roof, "Now Kṛṣṇa is coming back with His..." This is Kṛṣṇa consciousness. This is... Kṛṣṇa cannot be absent from a devotee when he's too much absorbed in Kṛṣṇa thought. This is the process of Kṛṣṇa consciousness.