In Vaishnava philosophy there are three ways for perfection- namely:
- sadhana-siddha, perfection attained by executing devotional service according to the rules and regulations.
- nitya-siddha, eternal perfection attained by never forgetting Krishna at any time.
- kripa-siddha, perfection attained by the mercy of the spiritual master or another Vaishnava.
Kaviraja Gosvami here stresses kripa-siddha, perfection by the mercy of superior authorities. This mercy does not depend on the qualifications of a devotee. By such mercy, even if a devotee is dumb he can speak or write to glorify the Lord splendidly, even if lame he can cross mountains, and even if blind he can see the stars in the sky.
———(Chaitanya-charitamrita Adi 8.5, Purport)
Sadhana-siddha refers to one who has become a devotee by regular execution of the regulative principles mentioned in the shastras, as ordered and directed by the Spiritual Master. If one regularly executes such devotional service, he will certainly attain perfection in due course of time. Everyone can become a sadhana-siddha, a devotee of the Lord, simply by association with the pure devotees.
———-(Reference: Srimad Bhagavatam 8.20.3)
Examples of Nitya-siddha devotees are His Divine Grace A.C. Bhaktivedanta Swami Srila Prabhupada, Sri Narada Muni, etc.,