Cladking is right and he knew all along....

[cladking]

In a very real way it might be said that understanding the PT the key "hole" is coming to understand the the word variously translated as "bow", "celestial expanse", "sky arc", "steps of light", and "light scatterer of the sky" is actually a rainbow.  Once you get this everything flows naturally.  

In the desert the geyser created truly dramatic rainbows around the primeval mound;

629a. Behold, thou art great and round like the "Great Round";
629b. behold, thou are bent around, and art round like the "Circle which encircles the nb.wt";
629c. behold, thou art round and great like the "Great Circle which sets."

The rainbow sets at noon. 

1487a. Thou art standing, Osiris; thy shadow is over thee, Osiris;

When the water stands its shadow is above it;



The rainbow was important to the ancients and they even used it to calculate the speed of light!!!