On first impression, Ancient Egyptian society may appear morbid, centring on mummification and the afterlife, but nothing could be further from the truth. The inhabitants of the Two Lands viewed the celebration of life as complementary to the ritual of death. The Opet, or Heavenly, Festival in particular, was a spectacular excuse to loosen the bonds of propriety.
The festival occurred in the second month of the season of Akhet, or July by our reckoning, and lasted from two to four weeks. It coincided with the helical rising of the exceptionally bright star Sirius, or Sothis as the Egyptians knew it, identified with the goddess Isis. This, in turn, marked the annual flooding of the Nile which was vital for agriculture and survival. It was also believed to represent the fathering of the Pharaoh by the mighty Amun-Ra himself.
From the Great Temple of Karnak the processional boat of the god Amun would be brought out bearing his image. Likewise a boat was carried from the nearby temple of Mut the Mother. When the two met on the avenue of the ram-headed sphinxes it signalled rejoicing, drunkenness and wild abandon as temple offerings were redistributed amongthe people.
At the climax of the festival the King entered the dark and shrouded inner sanctum of Amun where mysterious rites enabled him to take on aspects of eternity before returning to his people as a living god.
Source: Chronicles of Ancient Egypt by Jonathan Dee