The Book of the Heavenly Cow revolves around mankind's rebellion against Ra:
The central theme of The Book of the Heavenly Cow is mankind's rebellion against the elder sun god, Re, resulting in the punishment of humans by the fiery "eye" of Re in the form of the goddess Hathor. It takes place after Re's long rule on earth. The first part places considerable emphasis on the royal role of the sun god, who bears the royal title and who's name is surrounded by a cartouche. He is specifically given rulership over both the deities and the humans.
Prior to the rebellion, which required a complete reordering of the world, there had been a golden age where the various deities and humans were both under the sovereignty of the sun god. During this previous age, the sun god had not yet begun his daily course through the sky and the netherworld. Hence, there was no cycle of day and night, nor was there a netherworld and death did not exist.
Source: The Book of the Heavenly (Celestial) Cow, by Roland Mastaff. Tour Egypt.
Do we know the reason behind the rebellion? What compelled mankind to rise against Ra?