"Sri Caitanya Mahaprabhu has taken the position of Srimati Radharani -- how to feel separation from Krishna. This is Sri Caitanya Mahaprabhu. Therefore it is said, sri krsna caitanya radha krsna nahe anya. If you simply worship Sri Krsna Caitanya Mahaprabhu, then you will be able to worship both Radha and Krishna. This is the meaning of these verses. So Caitanya-caritamrta author, Krsnadasa Kaviraja Gosvami, is describing the cause of Sri Caitanya Mahaprabhu's appearance. The cause is that Krishna wanted to know, 'What is there in Radharani?'"
(Srila Prabhupada lecture, Mayapur, March 30, 1975)