Srila Bhaktisiddhanta Sarasvati Thakura in his Anubhasya commentary says that this stage-devotional service mixed with speculative knowledge-is also external and not within the jurisdiction of pure devotional service as practiced in Vaikunthaloka. As soon as there is some conception of materialistic thought-be it positive or negative-the service is not spiritual. It may be free from material contamination, but because there is mental speculation the devotional service is not pure and freed from the contamination of material life. A living entity who wants to be completely pure must be above this material conception. The negation of material existence does not necessarily mean spiritual existence. After material existence is negated, spiritual existence-namely sac-cid-ananda-still may not be manifest. Until one comes to the stage of actually understanding one's eternal relationship with the Supreme Lord, he cannot enter into spiritual life. Spiritual life means becoming detached from material life and engaging in the loving service of the Lord. Sri Caitanya Mahaprabhu therefore asked Ramananda Raya to explain something transcendental to devotional service mixed with speculative knowledge. A pure devotee is completely surrendered to the lotus feet of the Lord, and only by his love does he conquer Krsna, who cannot be conquered by anyone. Krsna always stands victorious over everything. No one can conquer Him. One can attain the stage of pure devotion simply by fully surrendering. This is next corroborated by Srimad-Bhagavatam (10.14.3), wherein Lord Brahma, defeated by the potency of Sri Krsna, fully surrendered unto the Lord.