The way of discussion with Dr. Staal requires a little bit of knowledge in the sastras which is called siddhanta. In the Caitanya Caritamrta it is said that nobody should be neglectful of the siddhanta because by siddhantic conclusion one becomes firm in Krsna Consciousness. So these siddhantic conclusions are being mentioned in all my books, and the boys and girls in our Krsna Society should now give more attention for studying the books very attentively. And to get the strength, one should chant the beads sixteen rounds without fail. In this way, when the devotee is constantly engaged in Krsna Consciousness, at that time, Krsna will give all intelligence from within how to make steady progress in Krsna Consciousness.
Letter to Krsnadevi, 17 February, 1970