Numbers in Birkat Kohanim
In Birkat Kohanim, the first line has 3 words, the second line 5 words, and the last line 7 words.
The steps the kohanim descended from the altar in the Temple were the same numbers.
We know that those numbers add up to 15, the numerical equivalent of a Hebrew Divine name, Yod Hey.
Centuries later, those numbers were repeated in the Tower of London of all places.
What is the origin of these numbers?