After going to Vṛndāvana, Rūpa Gosvāmī and Sanātana Gosvāmī preached devotional service and discovered many places of pilgrimage. They specifically initiated the service of Lord Madana-mohana and Lord Govindaji. Rūpa and Sanātana also brought many scriptures to Vṛndāvana. There they and the other members of the six Gosvāmīs studied various Vedic scriptures and picked up the essence of them, the devotional service of the Lord. Thus all the Gosvāmīs wrote many scriptures on devotional service based on the Vedic literature. In this way they delivered all the rascals and fallen souls.
Devotional service is not a sentimental activity. The essence of Vedic knowledge is devotional service, as confirmed in the Bhagavad-gītā. The Vedic literature aims at understanding Kṛṣṇa, and how to understand Kṛṣṇa through devotional service has been explained by Srila Rūpa Gosvāmī, Srila Sanātana Gosvāmī, and the other Gosvāmīs. 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.
The Gosvāmīs carried out the preaching work of devotional service on the basis of an analytical study of all confidential works of Vedic literature. This was in compliance with the order of Śrī Caitanya Mahāprabhu. Thus one can understand the most confidential devotional service of Vṛndāvana.