CC Madhya-lila 23.068 - Gautamiya-tantra
Sri Caitanya-caritamrta
CC Madhya-lila
CC Madhya 23.68, Translation and Purport:
“"The transcendental goddess Śrīmatī Rādhārāṇī is the direct counterpart of Lord Śrī Kṛṣṇa. She is the central figure for all the goddesses of fortune. She possesses all the attraction to attract the all-attractive Personality of Godhead. She is the primeval internal potency of the Lord."
This text is found in the Bṛhad-gautamīya-tantra. For an explanation, see Ādi-līlā 4.83–95.