"I offer my respectful obeisances unto the six Gosvamis--Sri Rupa Gosvami, Sri Sanatana Gosvami, Sri Raghunatha Bhatta Gosvami, Sri Raghunatha dasa Gosvami, Sri Jiva Gosvami, and Sri Gopala Bhatta Gosvami--who cast off all aristocratic association as insignificant. To deliver poor, conditioned souls, they accepted loincloths and became mendicants, but they were always merged in the ecstatic ocean of the gopis' love for Krsna, and they were always bathing repeatedly in the waves of that ocean."
Path of Perfection, Chapter 6
"There were six great Gosvamis of Vrndavana--Srila Rupa, Sanatana, Bhatta Raghunatha, Sri Jiva, Gopala Bhatta and Dasa Raghunatha--and none of them inherited the title of gosvami. All the Gosvamis of Vrndavana were bona fide spiritual masters situated on the highest platform of devotional service, and for that reason they were called gosvamis. All the temples of Vrndavana were certainly started by the six Gosvamis. Later the worship in the temples was entrusted to some householder disciples of the Gosvamis, and since then the hereditary title of gosvami has been used. However, only one who is a bona fide spiritual master expanding the cult of Sri Caitanya Mahaprabhu, the Krsna consciousness movement, and who is in full control of his senses can be addressed as a gosvami. Unfortunately, the hereditary process is going on; therefore at the present moment, in most cases the title is being misused due to ignorance of the word's etymology.
Caitanya-caritamrta, Madyam lila 9:289
"By the will of the supreme gardener, the branches of Srila Rupa Gosvami and Sanatana Gosvami grew many times over, expanding throughout the western countries and covering the entire region. Extending to the borders of the river Sindhu and the Himalayan Mountain valleys, these two branches expanded throughout India, including all the places of pilgrimage, such as Vrndavana, Mathura and Haridvara. The fruits of love of Godhead which fructified on these two branches were distributed in abundance. Tasting these fruits, everyone became mad after them.
The people in general on the western side of India were neither intelligent nor well behaved, but by the influence of Srila Rupa Gosvami and Sanatana Gosvami they were trained in devotional service and good behavior.
Caitanya-caritamrta, Adi lila, Chapter 10
"The six Gosvamis, namely, Sri Sanatana Gosvami, Sri Rupa Gosvami, Sri Raghunatha Bhatta Gosvami, Sri Raghunatha dasa Gosvami, Sri Jiva Gosvami, and Sri Gopala Bhatta Gosvami, are very expert in scrutinizingly studying the revealed scriptures with the aim of establishing eternal religious principles for the benefit of all human beings. They are always absorbed in the mood of the gopis and are engaged in the transcendental loving service of Radha and Krsna." (Sad-gosvamy-astaka 2)
Science of Self-Realization, Chapter 7
"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."
Caitanya-caritamrta, Madyam lila 1:33
"The Gosvamis, they left so many books handwritten, that when they were dispatched it was a full cartload, a big cartload, you see. Just imagine how many books they wrote. They were great scholars, and many varieties of books of bhakti school, Krsna consciousness, they wrote. So these Gosvamis were engaged, krsnotkirtana-gana-nartana, chanting and dancing. Kirtana means chanting, and nartana means dancing. Krsnotkirtana, utkirtana. Utkirtana means very loudly, not softly."
Srila Prabhupada Lecture, 11-18-68, Los Angeles
Bhaktivedanta Book Trust. HDG A.C. Bhaktivedanta Swami Srila Prabhupada.