In the Lalita-mādhava, Rūpa Gosvāmī explains that the movements of Kṛṣṇa’s eyebrows are just like the Yamunā and that the smiling of Rādhārāṇī is just like the moonshine. When the Yamunā and the moonshine come in contact on the bank of the river, the water tastes just like nectar, and drinking it gives great satisfaction. It is as cooling as piles of snow. Similarly, in the Padyāvalī, one constant companion of Rādhārāṇī says, “My dear moon-faced Rādhārāṇī, Your whole body appears very content, yet there are signs of tears in Your eyes. Your speech is faltering, and Your chest is also heaving. By all these signs I can understand that You must have heard the blowing of Kṛṣṇa’s flute, and as a result of this, Your heart is now melting.”
(Nectar of Devotion).