Srila Srinivasa Acarya has sung:

The six Gosvamis, under the direction of Srila Rupa Gosvami and Srila Sanatana Gosvami, studied various Vedic scriptures and picked up the essence of them, the devotional service of the Lord. This means that all the Gosvamis 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-gita (15.15): vedais ca sarvair aham eva vedyah. All the Vedic literature aims at understanding Krsna, and how to understand Krsna through devotional service has been explained by Srila Rupa and Sanatana Gosvamis, with evidence from all the Vedic scriptures. 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 Gosvamis.