Taking the part of Rādhārāṇī, Caitanya tries to love Kṛṣṇa as Rādhārāṇī loved Him. Kṛṣṇa was always amazed by Rādhārāṇī's love. "How does Rādhārāṇī give Me such pleasure?" He would ask. In order to study Rādhārāṇī, Kṛṣṇa lived in Her role and tried to understand Himself. This is the secret of Lord Caitanya's incarnation. Caitanya is Kṛṣṇa, but He has taken the mode or role of Rādhārāṇī to show us how to love Kṛṣṇa. Thus He is addressed: "I offer my respectful obeisances unto the Supreme Lord who is absorbed in Rādhārāṇī's thoughts."
This brings up the question of who Rādhārāṇī is and what Rādhā-Kṛṣṇa is. Actually Rādhā-Kṛṣṇa is the exchange of love. This is not ordinary love; Kṛṣṇa has immense potencies, of which three are principal: internal, external and marginal. In the internal potency there are three divisions: saṁvit, hlādinī and sandhinī. The hlādinī potency is the pleasure potency. All living entities have this pleasure-seeking potency, for all beings are trying to have pleasure. This is the very nature of the living entity. At present we are trying to enjoy our pleasure potency by means of the body in this material condition.