So just finished "A Thousand Sons"...

And it begs the questions - in the modern Chapters, why are there Librarians?

I went back and re-read Index Astartes III - and in that book, the Meeting at Nikaea resulted in Sorcery being banned. But in A Thousand Sons, this is ret-conned on page 355 - there are to be no Legion Librarius' and Psychic powers are banned from the Legions.

This is a bit stronger that IAIII.

So, _if_ this is true - how is it that today most of the chapters _do_ have Librarians, and some of them are using powers as strong as what 1K Sons used.

So for discussion:

a) McNeill over stepped himsefl in the book, and it is only Sorcery/Magic outlawed, psykers are still okay...
b) The Emperor himself later lightened the restrictions, in order to fight the Chaos Legions
c) The Psychic-using chapters ignored the edicts like the 1K Sons (just not as much), and over time, it worked itself back into the norm (since the Emperor isn't around to punish)
d) Someone else (Gullieman?) later reestablished the Librarians post Golden-throne.
e) Some of the chapters (Space Wolves) were a bit ignorant, and didn't think their powers (Rune-Priests) were Psychic powers, and thus didn't think the rule applied to them...and eventually it spread to other chapters...

Setting aside a. (because its no fun to discuss)... what do people think? If the novel "A Thousand Sons" is the proper canon... why would there be Librarians in the chapters today?

Just curious what people think.