In his book Siddhānta Ratna, Śrīpāda Baladeva Vidyābhūṣaṇa has written – eṣā tu bhaktis tan nitya parikaragaṇād ārabhyedānīntaneṣvapi tad bhakteṣu mandākinīva pracarati………sā tathābhūtā nitya dhāmni nitya pārṣadeṣu nityaṁ cakāsti surasarid iva tad bhakta praṇālyā prapañce’vatarati:

“This bhakti is being promulgated from the eternal associates of Śrī Hari down to the present day sādhaka bhaktas, like the current of the Mandākinī-river (the celestial Gaṅgā). bhakti is always present within the Lord’s eternal associates within the eternal abode, and flows down to the mundane world through the drain of Śrī Hari’s devotees like the stream of the Mandākinī.” 

The purport of this is that just as the current of the Mandākinī-river flows down from the Lord’s lotus feet to purify the three worlds – heaven, earth and hell -, similarly bhakti, which is the essential faculty of Śrī Hari’s transcendental intrinsic potency, flows down from Śrī Kṛṣṇa through the bhakta praṇālikā (the devotee-drain, or guru-praṇālikā, the succession of Gurus) to reach the hearts of all the devotees in the world. The sādhaka attains this Śrī Guru-praṇālī from the bona fide Guru. 

Nowadays, in this particular age of Kali, Śrīman Mahāprabhu is so kind to distribute Vraja’s lofty devotional service called mañjarī-bhāva-sādhanā, which is the essence of the transcendental erotic rasa, to the people of the world. 

 Those who wish to become blessed by commencing this mañjarī bhāva sādhanā, which is the unprecendented merciful gift of Śrīman Mahāprabhu, should take shelter of the lotus feet of such a Gauḍīya Vaiṣṇava Guru and receive the Śrī Guru Praṇālī and siddha praṇālī from him, as a basis for doing bhajana. 

 As a result of Śrī Guru sevā and Guru-bhakti, the sādhaka will easily be able to conquer all his bad habits and become blessed – this we have already mentioned before. Śrī Hari’s grace descends to the world in two streams – one is Śrī Vaiṣṇava and the other Śrī Guru. Through the glorious association of the Vaiṣṇavas, one learns about the obligation to take shelter of the lotus feet of Śrī Guru, and by the grace of the Vaiṣṇavas one actually attains shelter at the lotus feet of a bona fide Guru. 

By the grace of the Vaiṣṇavas, we attain the priceless treasure of Śrī Guru, who is the root cause of bhagavad bhajana. Therefore, the sādhakas who desire to attain prema should equally serve Śrī Guru and Śrī Vaiṣṇava. When the grace of the Vaiṣṇava, who is the bhagavad bhaktimaya vigraha, the full embodiment of devotion to God, and Śrī Guru, who is bhagavad bhaktimaya vigraha sākṣāt bhagavad avatāra, not only the full embodiment of devotion to God, but a direct incarnation of the Lord as well, meet each other, the bhakti sādhanā of the sādhaka will reach fulfilment. Hence Śrīla Narottama Ṭhākura Mahāśaya has written —  
chāḍiyā vaiṣṇava sevā, nistāra peyeche kevā, anukṣaṇa kheda uṭhe mane narottama dāse koy, jīvāra ucita noy śrī guru vaiṣṇava sevā vine   

“Who was ever redeemed without serving the Vaiṣṇavas? This grief constantly rises within my mind. Narottama dāsa says — “Life is not worth living without serving Śrī Guru and the Vaiṣṇavas.” 

 Śrī Bhagavān’s grace descends in two forms — Śrī Guru and Śrī Vaiṣṇava. Service toward Guru and Vaiṣṇava are both direct service to the Lord’s grace. If one is not there, the other remains incomplete. If Guru is served but there is no eagerness to serve the Vaiṣṇava, then the service of Guru is not complete; and when the Vaiṣṇavas are served, but there is no eagerness to serve the Guru, then there is also no full service to the Vaiṣṇavas. Therefore the bona fide Guru offers his surrendered disciple at the feet of the Śrī Vaiṣṇavas and orders him to be blessed with the association and the service of the Vaiṣṇavas, and the bona fide Vaiṣṇava also orders the devotee who surrenders unto him to become blessed by engaging in the service of Śrī Guru’s lotus feet.