Not sure if this is canon or not but the Emperor of Mankind came into existence when a bunch of human psykers committed mass suicide and formed the being known as The Emperor. This was, in what I judge, previous to the fall of the Eldar although not without, supposedly The Old Ones knowing what was going to happen to them. The Emperor has known from the start that he was going to have to fight Chaos so that is his primary goal, with the advancement of humankind filling the vacuum of power left by the Eldar... question is... did he know Horus would rebel and did he count on it kind of.. meaning did he know that the Imperium would be locked in a state where it could barely maintain dominance while fight The Great Enemy and also xenos so that it could not rebel in full force even from within? And why? Something that occurs to me lately is that maybe even though the Eldar have been the enemy they are one of the few races that see the true enemy in Chaos... perhaps the reason The Golden Throne is failing is because the total psyker energy in the universe (especially human based) is becoming less concentrated in the form of The Emperor as he ages on the throne. Even tho pyskers are sacrificed, perhaps their absolute energy is diminished because there are more and more among the populace... while the Eldar are finally allowing all their hopes to be set on the concentration of psykers (all eldar are psykers) to create Ynnead... I dunno; discuss! PS- I mean to post this in general
He did not foresee horus's rebellion. The emperor thought by abolishing religion he could starve out the chaos gods, he failed to realise that the chaos gods feed off humans every day activities. Not just worship. This is why he was shamed Lorgar so badly, because he was afraid that the worship Lorgar was spreading would feed the Chaos Gods. However, worship still has power. Instead of abolishing worship and leaving all that potential energy wasted he should've directed it unto himself so that he could be able to deal with Chaos. In essence it was kind of "Oh yea, my great crusade made chaos not a threat" Horus has turned to Chaos "Well how the heck did they have the power to do that?"
Interesting thought. Though if he did I don't think he'd let Horus live before the inevitable rebellion. Though, one thing I never understood was why he didn't tell his sons at least as to what he knew of the Chaos Gods. I think it would have saved Lorgar from his Heresy as opposed to just trying to kicking him in the teeth.
