Lord is the Purusha and hence Purusha shuktham is in HIS name. HE Incarnates to rescue us because we belong to HIM. Out of 3 gunas [viz Thamas, Satva, and Rajas], HE is an embodiment of Satva. When Sri Radha drank the hot milk, Sri Krishna's feet turned red. When inquired about the reason by Sridevi, Sri Krishna said, Sri Radha always thinks of his feet and hence the hotness of the milk had turned the color of his feet.