In a letter to Jayatirtha das written in Mumbai on 20th of November 1975, Srila Prabhupada is pointing out the essence of our preaching,...
The synthesis of absolute optimism in a spiritual sense and absolute negativism in material sense is unknown to those who don't carry the mercy of a pure devotee.
So powerful is Srila Prabhupada's voice and so powerful is sravanam, kirtanam, SRILA PRABHUPADA smaranam process of Krsna Consciousness.