The unification of Re and Osiris in the Netherworld

The unification of Re and Osiris is one of the most important and
complex topics in the ancient Egyptian religion. It is not only the
focal event of the Netherworldly journey of the sun, but one of the
most fundamental principles in all of Egyptian religion. Not
surprisingly, it is the primary focus of the corpus of Underworld
Books, as well as most funerary literature of the Third Intermediate
Period. Many cover this subject, but it still need more study. I
divided this study into the next specific points:
1- The reasons of the unification of Re and Osiris.
2- The time of this unification
3- The place of this unification.
4- The different interpretations of the relationship between Re
and Osiris.
5- The united ba.
6- The benefit from this unification in the interpretation of many
mysteries in the Egyptian religion.