pañca-sakhī madhye cāra, nitya-siddha rādhikāra se sakale sādhana nā koilo sakhī boli’ ukta jei, sādhana-prabhābe tei vraja-rāja pure bāsa pāilo
Amongst the five groups of Radharani’s sakhīs, four are eternally situated in their perfect roles (nitya-siddha). They did not have to perform any ritualistic sādhana to achieve their position. The fifth group is the gopis who have newly attained residence in Vraja by dint of their
sei sakhī dvi-prakāra, sādhanete siddha āra sādhana-para boliyā gaṇana siddha boli’ ākhya tāńra, gopī-deha hoilo jāńra kori’ rāge jugala-bhajana
These new sakhīs are of two varieties – those who are still performing sādhana in their present bodies as sadhaka manjaris and those who are already situated in their spiritual bodies beyond the rules of sādhana. Those who attain perfection and receive the body of a gopi are called siddha, and they continuously worship the Divine Couple in spontaneous love (raga).
kṛṣṇākṛṣṭa muni-jana, tathā upaniṣad-gaṇa je nā loilo gopīra svarūpa sādhana ābeśe bhaje, siddhi tabu nā upaje vraja-bhāva-prāpti aparūpa
There are many great saints who are attracted by Lord Krishna, but who haven’t achieved the topmost perfection of receiving the form of a gopi. The personified Upaniṣads are also in this category. Although they are all absorbed in their regulative worship of the Lord, their eternal spiritual siddhi still hasn’t fully awakened; for the mood of Vraja is very wonderful and rarely attained.
je je śruti-muni-gaṇa, gopī haya su-bhajana korilo sakhīra pada dhari’ nitya-sakhī-kṛpā-bale, tat-sālokya-lābha-phale sevā kore śrī-rādhā-śrī-hari
There were some great munis and personified śrutis who worshipped in the mood of the gopis, following in the footsteps of one of Radharani’s girlfriends. Then, by the power of that nitya-sakhī’s affectionate favor, they ultimately attained a residential place in that sakhī’s abode, where they eternally serve the Divine Couple Sri Radha and Sri Hari.
devī-gaṇa sei bhāve, sakhīra sālokya-lābhe kṛṣṇa-sevā kore sakhī ho’ye vrajera vidhāna ei, gopī binā āra keho nā pāibe vraja-juva–dvaye
Similarly, many groups of goddesses (devīs) have also become Radha’s sakhīs by this process. They are now absorbed in kṛṣṇa-sevā. This is how a sincere soul becomes one of Radharani’s eternal girlfriends – accepting the mood of a sakhī, one must render eternal service for the pleasure of Krishna in the abode of another sakhī. There is only one real principle which governs entrance into Vraja, that is, one must achieve the mercy of one of Srimati Radharani’s sakhīs. It is absolutely impossible for anyone to attain ecstatic eternal service of the young couple of Vraja in any other way.
—From Śrī Śrī Gītā-mālā » Part 4 » Rupanuga-bhajana-darpana » Song 18 » Translation by Dasaratha-suta dasa » Published by Nectar Books