"The Lord is all-pervading. As it is stated by Lord Krsna in the Bhagavad-gita, 'Everything is sustained by Me, but at the same time I am not in everything.' Since the Lord is all-pervading, there is nothing existing without His knowledge. The all-pervasive nature of the Supreme Personality of Godhead can never be within the limited knowledge of a living entity; therefore, a person who has attained steadiness of the mind by fixing the mind on the lotus feet of the Lord is able to understand the Supreme Lord to some extent. It is the business of the mind to wander over varied subject matter for sense gratification. Therefore only a person who engages the senses always in the service of the Lord can control the mind and be fixed at the lotus feet of the Lord. This concentration of the mind upon the lotus feet of the Lord is called samadhi. Until one reaches the stage of samadhi, or trance, he cannot understand the nature of the Supreme Personality of Godhead."
(KRSNA, The Supreme Personality of Godhead, Chapter 14)