Finished the puzzle but have a problem with preamble.
I don't see how the 'prominent 25' was associated
with the word at 6ac a century ago. (although I understand the other connections).
Boreas, having finished, I now see your point. All I can come up with, and it's pretty feeble. is that the seminal book (by the prominent...) refers to 25 D in its title!
Boreas - you have fallen right in the trap, I think. There are two pretty transparent hints in the thread, and, I think, you have ignored the significance of the clashes.