In His spiritual form, Kṛṣṇa enjoys His spiritual energy, and that is the sum and substance of the Rādhā-Kṛṣṇa pastimes. These pastimes can be understood only by elevated devotees. One should not try to understand the Rādhā-Kṛṣṇa potencies and pastimes from the mundane platform. Generally people misunderstand these as being material.
When the pleasure potency is further condensed, it is called mahābhāva. Śrīmatī Rādhārāṇī, the eternal consort of Kṛṣṇa, is the personification of that mahābhāva. In this regard, in the Ujjvala-nīlamaṇi (4.3) Rūpa Gosvāmī states that there are two competitors in loving Kṛṣṇa—Rādhārāṇī and Candrāvalī. When they are compared, it appears that Rādhārāṇī is superior, for She is mahābhāva-svarūpa. The term mahābhāva-svarūpa, "the personification of mahābhāva," is applicable to Rādhārāṇī only, and no one else. Mahābhāva is full of the pleasure potency, and it is an exhibition of the highest love for Kṛṣṇa. Rādhārāṇī is therefore known throughout the world as the most beloved of Kṛṣṇa, and Her name is always associated with Kṛṣṇa as Rādhā-Kṛṣṇa.
The Brahma-saṁhitā (5.37) also confirms that Kṛṣṇa expands Himself by His pleasure potency in the spiritual world and that these potencies are all nondifferent from Him, the Absolute Truth. Although Kṛṣṇa is always enjoying the company of His pleasure-potency expansions, He is all-pervading. Therefore Brahmā offers his respectful obeisances to Govinda, the cause of all causes.
As Kṛṣṇa is the highest emblem of spiritual perfection, so Rādhārāṇī is the highest emblem of the spiritual pleasure potency meant for satisfying Kṛṣṇa. Kṛṣṇa is unlimited, and Rādhārāṇī is also unlimited in Her ability to satisfy Him. Kṛṣṇa is satisfied just by seeing Rādhārāṇī, but Rādhārāṇī expands Herself in such a way that Kṛṣṇa desires to enjoy Her more. Because Kṛṣṇa was unable to estimate the pleasure potency of Rādhārāṇī, He decided to accept the role of Rādhārāṇī, and that combination of Kṛṣṇa and Rādhārāṇī is Śrī Caitanya Mahāprabhu.