There is a Bengali song by Srila Bhaktisiddhanta Sarasvati Thakura which goes as follows:
mahaprabhu sri caitanya, radha-krsna
rupanuga janera jivan
"Mahaprabhu Sri Caitanya, who is non-different from Sri Sri Radha and Krsna, is the very life of those Vaisnavas who follow Srila Rupa Gosvami." (Sri Guru-parampara)
Those who follow the teachings of Srila Rupa Gosvami are known as rupanugas. Srila Rupa Gosvami was the chief disciple of Sri Caitanya Mahaprabhu and it was he whom Mahaprabhu chose to head the generations of future followers and worshippers of Sri Sri Radha and Krsna.
Once, while living in Puri, Srila Rupa Gosvami composed a verse and after writing it on a palm leaf scroll, he went to bathe in the ocean. At that time, Sri Caitanya Mahaprabhu visited the residence of Srila Rupa Gosvami and saw the verse written on the palm leaf:
'yam krsnah saha-cari kuru-ksetra-militas
tathaham sa radha tad idam ubhayoh sangama-sukham
mano me kalindi-pulina-vipinaya sprhayati
“O my friend, now I have met My beloved Kṛṣṇa at Kuruksetra. I am that same Radha, and now that We are meeting together it is most wonderful. Still, within I desire to go to the bank of the River Yamuna and under the shade of the trees I wish to hear Him play the fifth note of His sweet flute which charms the mind.” (Cc. Antya 1.79)
Sri Caitanya Mahaprabhu read this verse and was overwhelmed by ecstatic love. When Srila Rupa Gosvami returned, Mahaprabhu slapped him mildly and said, “My heart is very confidential. How did you know My mind in this way?” After saying this the Lord firmly embraced Srila Rupa Gosvami.
Mahaprabhu then inquired from Svarupa-damodara, “How could Rupa understand My heart?”
Svarupa-damodara replied, “I can understand that You have already bestowed Your causeless mercy upon him, otherwise it would not be possible for Rupa to have understood You.”
Thereupon, Mahaprabhu was very pleased and requested Svarupa-damodara to kindly give further instructions to Rupa in the matter of transcendental mellows (rasa).
After some time, Mahaprabhu came to visit Srila Rupa Gosvami accompanied by Svarupa-damodara, Ramananda Raya and other intimate devotees. Mahaprabhu requested Srila Rupa Gosvami to read a number of verses that he had composed. Being very humble and shy by nature, Srila Rupa Gosvami remained silent. Svarupa-damodara then read the previous verse compiled by Sri Rupa which was so much liked by Mahaprabhu as well as the following verse:
ratim vitanute tundavali-labdhaye
karna-kroda-kadambini ghatayate karnarbudebhyah sprham
cetah-prangaṇa-sangini vijayate sarvendriyanam krtim
no jane janita kiyadbhir amrtaih krsneti varna-dvayi
“I do not know how much nectar the two syllables 'Krs-na' have produced. When it is chanted, it seems to dance within my mouth. I then desire thousands of mouths. When that name enters my ears, I desire millions of ears. And when the name dances in the courtyard of the heart, it conquers the activities of the mind, and all the senses become paralyzed.” (Cc. Antya 1.99)
Hearing these and many more verses compiled by Srila Rupa Gosvami, all the Vaisnavas became jubilant. Ramananda Raya especially showed interest in the writings of Srila Rupa Gosvami and being very pleased with him, began to praise the qualities of Sri Rupa as if he had a thousand mouths. Ramananda Raya said, “This is not a poetic presentation. It is a continuous shower of nectar. Indeed, it is the essence of all ultimate realizations. The wonderful descriptions of Rupa are superb arrangements to express transcendental loving affairs of Radha and Krsna. Hearing them will plunge the heart and ears of everyone into a whirlpool of supreme transcendental bliss.”
The significance of the praises of Srila Rupa Gosvami offered by Svarupa-damodara and Ramananda Raya may be considerably more meaningful to the readers when we take into account the ontological hierarchy in the spiritual world. According to Srila Kavi Karnapura, the author of Gaura-ganoddesa-dipika, it is said that in krsna-lila, Ramananda Raya was the gopi named Visakha and Svarupa-damodara was the gopi named Lalita-sakhi. Both Lalita and Visakha are the very intimate associates of Srimati Radharani, who alone can satisfy the desires of Lord Madhava. Lalita and Visakha are considered the personal expansions of the serving mood of Srimati Radharani, thus they are the two chief assistants in the madhurya-rasa – the love affairs between Radha and Krsna.
Directly serving under Lalita-sakhi in the madhurya-rasa are the manjaris, i.e. the younger cowherd girls. This manjari group of servitors mainly consists of new recruits in the madhurya-rasa and due to their young age, they have been given the most sacred type of pure service to Radha and Krsna. The service performed by the manjari class we are to conceive most respectfully and attentively.
When Radha and Krsna are in secrecy, in a private place, the older sakhis do not like to approach the Divine Couple at that time for fear of causing a slight disturbance. Radha and Krsna may feel some shyness in the presence of the older sakhis. But the younger gopis, the manjaris, can enter there without disturbing the free mixing of Radha and Krsna. This manjari group of servitors in the madhurya-rasa is headed by the gopi named Rupa-manjari. To perform their service, the manjaris headed by Rupa-manjari, sometimes go to that place where Radha and Krsna are intimately engaged in divine love dalliances. Such a high and intimate scope of service is available to no other group of servitors than that of the manjaris. Rupa-manjari, who leads the manjari group, has appeared in gaura-lila as Srila Rupa Gosvami and Sri Caitanya Mahaprabhu has given him the supreme position as head of the Gaudiya sampradaya (rupanuga-sampradaya).
As Srila Bhakti Raksaka Sridhara Deva Gosvami Maharaja used to say:
“The camp, the sampradaya of Sri Caitanya Mahaprabhu is known as the rupanuga-sampradaya. There our fate and our fortune is located. Now we have to conduct ourselves in such a way that naturally we can connect with that highest, purest spiritual conception from here. We must not allow ourselves to be satisfied with anything less than this highest ideal. That should be the highest goal of our life.”
So, the real meaning of rupanuga-bhajana is nothing less than that – the highest ideal of the highest spiritual conception. Following in the footsteps of Srila Rupa Gosvami ever desiring his mercy, falling prostrate at his lotus feet and praying again and again and again to be enlisted in his group of servitors. That is rupanuga-bhajana.