As soon as you are engaged in the service, loving service of the Supreme Personality of Godhead, immediately you feel liberation. This is practically. When you are fully engaged in Krsna consciousness, even if you walk on the street, you’ll feel that “I am separate from these persons. I am in a, I am walking on a different path.” This is the feeling. Bhaktih paresanubhavah. This is bhakti. Paresanubhavah. You will experience yourself. That is the test. If you experience yourself that “I am different from these persons,” then where is the attachment for material things? So that is the test; how much you have become advanced in devotional service, you can experience yourself. The example is given: Just like a hungry man, if he’s given food, if he eats, then he experiences himself that he’s getting strength, his hunger is being satisfied. The, these things will be experienced. He hasn’t got to take certificate from others, “Whether I am advancing in spiritual consciousness, Krsna consciousness.” He’ll feel himself. Bhaktih paresanubhava viraktir anyatra syat. This is the test.
From Srila Prabhupada’s lecture, Vrndavana, October 21, 1972