The influence of a pure devotee is such that if someone comes to associate with him with a little faith, one gets the chance of hearing about the Lord from authoritative scriptures like Bhagavad Gita and Srimad Bhagavatam.
Simply by the association of pure devotees one can understand the transcendental name, fame, quality and activities of the Supreme Personality of Godhead.
Simply by associating with a pure devotee, one becomes wonderfully advanced in Krishna Consciousness. Sadhu-sanga, or association with a devotee, means always engaging in Krishna Consciousness by chanting the Hare Krishna mantra but he whose heart is contaminated sees things differently. Therefore by sat-sanga, or association with devotees, one becomes perfectly pure in heart.
Only in the association of pure devotees can the words of Lord Krishna be fully potent and relishable to the heart and ear. Dhruva Maharaja explicitly wanted the association of devotees. That association in devotional activities is just like the waves of an incessantly flowing river.
A devotee searches out a pure devotee and simply by his association becomes more advanced in spiritual consciousness than any yogi.
To understand the personal activities of the Lord, one has to seek the association of devotees and by such association, when one contemplates and tries to understand the transcendental activities of the Lord, the path to liberation is open and he is freed.