Ezekiel tells us that rainbows proclaim God's spender.
In his Divine Comedy" Dante said something of the same thing. There, Dante, on arrival in Paradise, was stricken by the way that while all of heaven was new to him, it somehow reminded him of the best things he saw on earth.
He went to the heavenly Beatrice for an explanation of this, and she answered. 'All things among themselves possess an order, and this order is the form that makes the universe like God.
Returning to today's reading, its rainbow proclaims God's glory by its perfect orderliness. Every rainbow has the same orderly spectrum, passing from red to orange, to yellow, to green. That orderliness mirrors the orderliness of God. likewise, the orderly sequence from do to re, to mi is the musical scale reflects the orderliness of God.