This verse is found in the Bhakti-rasamrta-sindhu (1.2.2). Because living entities are minute, atomic parts and parcels of the Lord, devotional service is already present within them in a dormant condition. Devotional service begins with sravana kirtana, hearing and chanting. When a man is sleeping, he can be awakened by sound vibration; therefore every conditioned soul should be given the chance to hear the Hare Krsna mantra chanted by a pure Vaisnava. One who hears the Hare Krsna mantra thus vibrated is awakened to spiritual consciousness, or Krsna consciousness. In this way one's mind gradually becomes purified, as stated by Sri Caitanya Mahaprabhu (ceto-darpana-marjanam). When the mind is purified, the senses are also purified. Instead of using the senses for sense gratification, the awakened devotee employs the senses in the transcendental loving service of the Lord. This is the process by which dormant love for Krsna is awakened.