" He had always wanted the world to be just like that – no doubts, no lingering areas of hesitation or equivocation, just action, purity of will and deed, the knowledge that whatever he did could never be, and could never have been, otherwise. From the first day of this rebellion, everything had shaken that single-mindedness. The things he had relied on with total surety had proven to be illusory and weak, and things he had thought of as being fictive and simple-minded had proved to have unexpected power. He had been forced to recalibrate, to reorientate. As every sword-brother knew, the time of greatest weakness was during the correction of a defective technique. He had started to fight… and lose. He had faced Horus Aximand and had been made to withdraw. He had faced Khârn, whom he had not yet been able to bring himself to hate fully, and been beaten. He had even taken on a primarch. Had that been hubris? Or just frustration, a desperate bid to recover his now-so-elusive sense of superiority? If he had somehow done the impossible and bested Fulgrim, would that have finally banished the whispers of doubt?
Probably not. The fault had never been external, he knew now – it had always been within him, slowly metastasising, becoming impassable the longer he ignored it. He had needed to hear Dorn’s words of release to understand it. They had, all of them, been fighting with one hand behind their backs, trying to hold on to a dream that had already died. The enemy was utterly changed now. They were physically stronger and morally intoxicated, eagerly drinking up gifts that should have been shunned as poison. And yet, those who remained loyal had tried to cling on to what they had been at the very start. They had still mouthed pieties about Unity and the Imperial Truth long after fealty to such virtues had become impossible. Once he grasped that, once he faced up to it, he had what he needed to remove the fetters in his mind.
I no longer fight for the Imperium that was, he told himself. I fight for the Imperium as it will become. "

― , Warhawk (The Siege of Terra #6)