Advancement in the transcendental loving service
Srimad-Bhagavatam
SB Canto 2
The Lord is unlimited; no one can know Him completely, but one's advancement in the transcendental loving service of the Lord can make one eligible to know the Lord
SB 2.9.32, Purport: The secret of success in understanding the intricacies of knowledge of the Absolute Truth, the Personality of Godhead, is the causeless mercy of the Lord. Even in the material world, the father of many sons discloses the secret of his position to the pet sons. The father discloses the confidence unto the son whom he thinks worthy. An important man in the social order can be known by his mercy only. Similarly, one must be very dear to the Lord in order to know the Lord. The Lord is unlimited; no one can know Him completely, but one's advancement in the transcendental loving service of the Lord can make one eligible to know the Lord. Here we can see that the Lord is sufficiently pleased with Brahmājī, and therefore He offers His causeless mercy to him so that Brahmājī may have the factual realization of the Lord by His mercy only.