Verse 10 kṛṣṇa-bhakti-janma-mūla

Chaitanya Charitamrta Madhya Lila 22.83

kṛṣṇa-bhakti-janma-mūla haya 'sādhu-saṅga'

kṛṣṇa-prema janme, teṅho punaḥ mukhya aṅga

kṛṣṇa-bhakti — of devotional service to Kṛṣṇa; janma-mūla — the root cause; haya — is; sādhu-saṅga — association with advanced devotees; kṛṣṇa-prema — love of Kṛṣṇa; janme — awakens; teṅho — that same association with devotees; punaḥ — again; mukhya aṅga — the chief principle.

"The root cause of devotional service to Lord Kṛṣṇa is association with advanced devotees. Even when one's dormant love for Kṛṣṇa awakens, association with devotees is still most essential.

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Kishori Mohan Prabhu's summary of some Harikatha by Srila Bhakti Vigyan Bharati Maharaj on Dec 2, 2012. 

Srila Bhaktivedanta Narayan Maharaj's 21 June 2004 Italian talk "How to pull on the rope" about sadhu-sanga in preface to talking about Ratha Yatra. References several of our previous verses. 

Satyaraj Das ACBSP in BTG 2017 "From Osmosis to Perfection: The importance of Sadhu Sanga."