CC Madhya 1.33
mūḍha adhama-janere teṅho karilā nistāra
Śrīla Śrīnivāsa Ācārya has sung:
lokānāṁ hita-kāriṇau tri-bhuvane mānyau śaraṇyākarau
vande rūpa-sanātanau raghu-yugau śrī-jīva-gopālakau
The six Gosvāmīs, under the direction of Śrīla Rūpa Gosvāmī and Śrīla Sanātana Gosvāmī, studied various Vedic literatures and picked up the essence of them, the devotional service of the Lord. This means that all the Gosvāmīs wrote many scriptures on devotional service with the support of the Vedic literature. Devotional service is not a sentimental activity. The essence of Vedic knowledge is devotional service, as confirmed in the Bhagavad-gītā (15.15): vedaiś ca sarvair aham eva vedyaḥ. All the Vedic literature aims at understanding Kṛṣṇa, and how to understand Kṛṣṇa through devotional service has been explained by Śrīla Rūpa and Sanātana Gosvāmīs, with evidence from all Vedic literatures. They have put it so nicely that even a rascal or first-class fool can be delivered by devotional service under the guidance of the Gosvāmīs.