Any crystalline group of musical words has had a long and still period to form in.
Here is one theory.
But there is a larger law which perhaps comprehends these facts.
It is this.

The rapidity with which ideas grow old in our memories is in a direct ratio to the squares of their importance.

Their apparent age runs up miraculously, like the value of diamonds, as they increase in magnitude.

A great calamity, for instance, is as old as the trilobites an hour after it has happened.

It stains backward through all the leaves we have turned over in the book of life, before its blot of tears or of blood is dry on the page we are turning.