Guilliman followed the priest’s gaze around the high stacks. ‘Knowledge is power, and my own is lacking. I have a great deal to understand before I can begin to rebuild the Imperium. To that end, I am collecting as many histories of as many worlds as I can. I will use them to model the last ten millennia so that I might study it, and from it make a true history, the like of which has not been written for thousands of years. By doing so, I will understand what went wrong with my father’s plans, and be able to formulate a correction.’

‘You speak plainly.’

‘Nothing is gained through obfuscation,’ said Guilliman. ‘Time is short. Why would I lie?’

‘I see.’ Mathieu paused again. ‘I beg your pardon for my impertinence, my lord–’

‘You are aware enough to recognise impertinence, yet still you proceed,’ interrupted Guilliman testily. ‘Ask me, or do not. There can be no secrets between you and I if you are to serve me effectively.’

‘My apologies,’ the priest said smoothly. Frater Mathieu’s peaceful face showed the barest sign of strain, a tick under one eye.

Guilliman noticed it. Irritated with himself for putting the man on edge, he leaned back in his chair, adopting a remarkably human posture for one so inhuman. He folded his hands in his lap.

‘Let us start anew,’ Guilliman said. ‘It is I who should apologise. A man may hold a different point of view to another. It is no excuse for ill manners. Once, I was more even-tempered. But now…’ Guilliman trailed off, his eyes straying over the mounded remains of ten millennia of history. ‘Things are not what they were. I am not who I was. I am pressed on all sides. I let my temper get the better of me. It is late, and there is so much to do.’ He shook his head and attempted to smile. ‘Please, priest, your impertinence – voice it openly.’

Frater Mathieu relaxed, a change in posture imperceptible to a normal man, but clear to the primarch. The flicker of a decision being made passed over his face. Again, the priest considered his next words carefully.

‘There is an element of hypocrisy to your activities, my lord. You ordered the doors to the Library of Ptolemy on Macragge barred, pronouncing the time of learning done, but here you devote yourself to the pursuit of history.’

Guilliman made a reasonable face, conceding the point. ‘I stand by my actions. One day, those doors will be unbarred. What I did there was symbolic. Who even in my own realm read and understood what the library contained? I sealed the doors not against the truth, but against the superstition that has taken truth’s place.’