Modern Egyptologists evaluate Herodotus's and Diodorus's stories as some sort of defamation, based on both authors' contemporary philosophy. They call for caution against the credibility of the ancient traditions. They argue that the classical authors lived around 2000 years after Khufu, and their sources that were available in their lifetimes surely were antiquated. Additionally some Egyptologists point out that the philosophies of the ancient Egyptians had changed since the Old Kingdom. Oversized tombs such as the Giza pyramids must have appalled the Greeks and even the later priests of the New Kingdom, because they remembered the heretic pharaoh Akhenaten and his megalomaniac building projects. This negative picture was presumably projected onto Khufu and his pyramid. The view was possibly promoted by the fact that during Khufu's lifetime, permission for the creation of oversized statues made of precious stone and their displaying in public was limited to the king. In their era, the Greek authors, mortuary priests, and temple priests could only explain the impressive monuments and statues of Khufu as the result of a megalomaniac. These negative evaluations were applied to Khufu.