CC Ādi 17.75

jñāna-karma-yoga-dharme nahe kṛṣṇa vaśa
kṛṣṇa-vaśa-hetu eka — prema-bhakti-rasa
Synonyms: 
jñāna — the path of speculative knowledge; karma — fruitive activities; yoga — the process of controlling the senses; dharme — in the activities, in such an occupation; nahe — is not; kṛṣṇa — Lord Kṛṣṇa; vaśa — pleased; kṛṣṇa — of Lord Kṛṣṇa; vaśa — for the pleasure; hetu — reason; eka — one; prema — love; bhakti — devotional service; rasa — such a mellow.
Translation: 
“By following the paths of speculative philosophical knowledge, fruitive activity or mystic yoga to control the senses, one cannot satisfy Kṛṣṇa, the Supreme Lord. Unalloyed devotional love for Kṛṣṇa is the only cause for the Lord’s satisfaction.