Bottom line is... techn. books were not "initially" designed for the student, but were there as a " guide" for prof. exam purposes, and to standardise technique .
And, the descriptions in both tomes, makes it evident, that in the hands of students ( and even some prof. ) the underlying meanings are sometimes completely lost.
They are at best GUIDES , and to literally describe even a basic feather, as you know , could occupy a whole page .
My suggestion to anyone who is studying the rudiments of the Standard dances, would be well served to read and digest Scriveners " Just One Idea " .