CC Ādi 4.226

sei dvāre pravartāila kali-yuga-dharma
caitanyera dāse jāne ei saba marma
Synonyms: 
sei dvāre — in that way; pravartāila — He initiated; kali-yuga — of the Age of Kali; dharma — the religion; caitanyera — of Lord Caitanya Mahāprabhu; dāse — the servant; jāne — knows; ei — these; saba — all; marma — secrets.
Translation: 
Thus He initiated the dharma for the Age of Kali. The devotees of Lord Caitanya know all these truths.
Purport: 

Lord Caitanya is Śrī Kṛṣṇa Himself, the absolute enjoyer of the love of the gopīs. He Himself assumes the role of the gopīs to taste the predominated happiness of transcendental mellows. He appeared in that mode, but simultaneously He propagated the religious process for this age in a most fascinating way. Only the confidential devotees of Śrī Caitanya Mahāprabhu can understand this transcendental secret.