One can understand Krishna only by serving a pure devotee.
To save oneself, one must take shelter of a pure devotee. Narottama dasa Thakura therefore says, chadiya vaisnava-seva nistara payeche keba. If one wants to save himself from material nature’s onslaughts, which arise because of the material body, one must become Krishna conscious and try to fully understand Krishna. As stated in Bhagavad-gita (4.9), janma karma ca me divyam evam yo vetti tattvatah. One should understand Krishna in truth, and this one can do only by serving a pure devotee. Thus Prahlada Maharaja prays that Lord Nrsimhadeva place him in touch with a pure devotee and servant instead of awarding him material opulence. Every intelligent man within this material world must follow Prahlada Maharaja. Mahajano yena gatah sa panthah. Prahlada Maharaja did not want to enjoy the estate left by his father; rather, he wanted to become a servant of the servant of the Lord. The illusory human civilization that perpetually endeavors for happiness through material advancement is rejected by Prahlada Maharaja and those who strictly follow in his footsteps. There are different types of material opulence, known technically as bhukti, mukti and siddhi. Bhukti refers to being situated in a very good position, like a position with the demigods in the higher planetary systems, where one can enjoy material sense gratification to the greatest extent. Mukti refers to being disgusted with material advancement and thus desiring to become one with the Supreme. Siddhi refers to executing a severe type of meditation, like that of the yogis, to attain eight kinds of perfection (anima, laghima, mahima, etc.). All who desire some material advancement through bhukti, mukti or siddhi are punishable in due course of time, and they return to material activities. Prahlada Maharaja rejected them all; he simply wanted to engage as an apprentice under the guidance of a pure devotee.
Source: A.C. Bhaktivedanta Swami Prabhupada (2014 edition), “Srimad Bhagavatam”, Seventh Canto, Chapter 09 – Text 24