Srila Narottama dasa Thakura says in this connection, chadiya vaisnava-seva nistara peyeche keba: “Unless one serves the spiritual master and acaryas, one cannot be liberated.” Elsewhere he says:

ei chaya gosani yanra — mui tanra dasa
tan-sabara pada-renu mora panca-grasa

“I simply accept a person who follows in the footsteps of the Six Gosvamis, and the dust of such a person’s lotus feet is my food.”

From Srila Prabhupada’s purport to Cc Adi 8.7