SB 1.5 - Pure devotion is infectious
The Lord is the purest entity, and unless one is equally pure from the infection of material qualities, one cannot become a pure devotee of the Lord. The bhakti-vedāntas were pure devotees, and by their association and by eating once the remnants of their foodstuff, Nārada became purified in heart. At that time the very nature of the transcendentalist became attractive to him. Having developed an inclination for bhakti, being pure in mind, taste for devotional processes developed in Nārada’s mind. The neophyte devotee becomes enriched with the transcendental qualities of the pure devotee, which means attraction to the name, fame, quality, pastimes etc of the Supreme Lord. Here the next five stage of bhakti are mentioned: desire to worship, bhakti, anartha-nivṛtti, niṣṭhā and ruci. After the elimination of all sins, one becomes attracted, one can have steadiness, one can have perfect taste, one can have transcendental emotions, and at last one can be situated in the plane of loving service of the Lord. All these stages develop by the association of pure devotees.