nasnatah pathyam evannam
vyadhayo ’bhibhavanti hi
evam niyamakrd rajan
sanaih ksemaya kalpate
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
My dear King, if a diseased person eats the pure, uncontaminated food prescribed by a physician, he is gradually cured, and the infection of disease can no longer touch him. Similarly, if one follows the regulative principles of knowledge, he gradually progresses toward liberation from material contamination.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
One is gradually purified if one cultivates knowledge, even through mental speculation, and strictly follows the regulative principles enjoined in the sastras and explained in the next verse. Therefore the platform of jñana, speculative knowledge, is better than the platform of karma, fruitive action. There is every chance of falling from the platform of karma to hellish conditions, but on the platform of jñana one is saved from hellish life, although one is still not completely free from infection. The difficulty is that on the platform of jñana one thinks that he has been liberated and has become Narayana, or Bhagavan. This is another phase of ignorance.
ye ’nye ’ravindaksa vimukta-maninas
tvayy asta-bhavad avisuddha-buddhayah
aruhya krcchrena param padam tatah
patanty adho ’nadrta-yusmad-anghrayah
Because of ignorance, one speculatively thinks himself liberated from material contamination although actually he is not. Therefore even if one rises to brahma jñana, understanding of Brahman, one nevertheless falls down because of not taking shelter of the lotus feet of Krsna. Nonetheless, jñanis at least know what is sinful and what is pious, and they very cautiously act according to the injunctions of the sastras.