CC Madhya 21.119

karma, tapa, yoga, jñāna,vidhi-bhakti, japa, dhyāna,
ihā haite mādhurya durlabha
kevala ye rāga-mārge,
bhaje kṛṣṇe anurāge,
tāre kṛṣṇa-mādhurya sulabha
Word for word: 
karma — fruitive activities; tapa — austerities; yoga — the practice of mystic yoga; jñāna — speculative cultivation of knowledge; vidhi-bhakti — regulative principles in devotional service; japa — chanting; dhyāna — meditation; ihā haite — from these things; mādhurya — the sweetness of Kṛṣṇa; durlabha — very difficult to perceive; kevala — only; ye — one who; rāga-mārge — by the path of spontaneous ecstatic love; bhaje — worships; kṛṣṇe — Lord Kṛṣṇa; anurāge — with transcendental feeling; tāre — unto him; kṛṣṇa-mādhurya — the sweetness of Kṛṣṇa’s; sulabha — very easily appreciated.
Translation: 
“The transcendental mellows generated from the dealings between the gopīs and Kṛṣṇa cannot be tasted by means of fruitive activity, yogic austerities, speculative knowledge, regulative devotional service, mantra-yoga or meditation. This sweetness can be tasted only through the spontaneous love of liberated persons who chant the holy names with great ecstatic love.