Prabhupada Letters :: 1969.

"You have asked, is it true that the Spiritual Master remains in the material universe until all of His disciples are transferred to the Spiritual Sky? The answer is yes, this is the rule।"

Prabhupada Letters :: 1968.

"Our mission is to reach the Supreme Planet, in the Spiritual Sky, namely the Abode of Krishna। As such, we cannot compromise that all sorts of meditation gives the same result. There is no Vedic evidence, neither any proof of the Acharya principles."