"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?' He is Madana-mohana. Krishna's another name is... He's attractive. Krishna is attractive to everyone, even He is attractive to Cupid, Madana. Madana is attractive in the material world, and He is Madana-mohana. And Radharani is Madana-mohana-mohini, means She attracts even the Madana-mohana. Therefore Krishna is trying to understand, 'What is there in Radharani that She attracts? I attract the whole universe, and She attracts Me.'"
(Srila Prabhupada lecture, Mayapur, March 30, 1975)