This new understanding of the rainbow and its "shadow" are opening up several new lines and casting already solved lines in a new light. It is also providing more context and the ancient language was highly context dependent. My initial belief was finding that osiris' shadow was above him would solve only a single line but the effects are snowballing.

Revisiting utterance #570 with this new understanding brings forth quite a lot of new meaning. I know people don't like long stretches of utterances so I'm going to delete a lot of it so it's easier to follow.

Utterance 570.

1443a. To say: The face of heaven is washed; the vault of heaven is bright;

The rainbow is brighter as the face of heaven (81' 3") is washed.

1443b. a god is brought to birth by the sky upon the arms of Shu and Tefnut, upon the arms of N.

Shu takes the water up and tefnut brings the spray down.

1444a. "Great wbn," say the gods;

The rainbow and the new god (N) rise.

...

1445a. "Khepri, hear it, this word, which is spoken to thee by N.;
1445b. let thy heart be glad for N., for N. is a Great One, the son of a Great One;
1445c. N. is with thee; take him with thee."

1446a. "Nun, hear it, this word, which is spoken to thee by N.;
1446b. let thy heart be glad for N., for N. is a Great One, the son of a Great One;
1446c. N. is with thee; take him with thee."

1447a. "Atum, hear it, this word, which is spoken to thee by N.;
1447b. let thy heart be glad for N., for N. is a Great One, the son of a Great One;
1447c. N. is with thee; take him with thee."

Khepri (mid day sun), nun (water), and atum (spraying water) accept the dead king as one of their own (a force of nature).

...

1449a. Mayest thou be near to N., in thy name of "Rē‘"; drive thou away the garments (darkness) of the sky.

The rainbow disappears at noon when khepri comes to rule the sky. He drives away the rainbow (garment), and perhaps, the darkness (the shadow above the rainbow.

...

1455a. for N. is a star, the light-scatterer of the sky.

The dead king not only is remembered by being assigned a specific star as a mnemonic but he is the stars or spirits (CO2) which causes the water to fly to heaven. These bubbles and droplettes in the air scatter the light of the sun into the rainbow and osiris' shadow above.

1459a. N. seizes the white crown; that upon which is the wire of the green crown.

The dead king as the water wears the crown on top which contains the rainbow. The green crown contains the white crown of water and is operated by the wire. This is simply a reference to the upper eye of horus in the mehet weret cow.

1460a. N. is this (kind of) colour which comes out of Nun.

ROY G BIV



...

1465d. N. appears in the eastern side of the sky,

1465e. like Rē‘ who shines in the eastern side of the sky.

The dead king appears in the morning on the eastern side of "heaven" as does the sun.

This is very much the rainbow utterance. It was read to the crowds before noon at the ascension ceremony.

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Man fears the pyramid, time fears man.