The Emperor nodded. ‘This is not real. We do not stand here. I am not your father. All of this is promise to come. Its possibility is fragile. It comes from you, and it is up to you. If you wish me to live, if you wish this reality to be, and for the Emperor to stand as I stand, and speak to you as I do, then you must decide. Yours is the hand that must change your destiny.’ The Emperor looked solemn. ‘It would be easy to let time unfold as you have long believed it would. So many events pull us to your death and mine. The resistance is difficult. You must push against currents that serve gods.’

‘No,’ Sanguinius said, though he was uncertain. ‘There is too much here that flatters my pride. ’

‘You cannot divorce yourself from your perception of reality, or of many realities. You are your own filter. I am as you see me because this is how you see me.’

Sanguinius took a step backwards. He brushed against a column. The contact of shoulder against marble was reassuring. He wanted to believe what the Emperor was saying.

It is because you want to believe it that you must not.

This is the choice. The whisper in his mind was urgent. This time, he did not know if the voice came from without, or if he was speaking to himself. The voice was telling the truth. What might be a lie was the way the choice was presented.

‘You are the salvation of the Imperium,’ the Emperor said. ‘Your pride and the truth are not opposed. Embrace what must be done.’

‘I am not its salvation.’

‘Will you doom the Imperium, then? Will you compound the sin of the Imperium Secundus by turning away from your duty? Will you not answer my call?’

The wind grew stronger. The light in the garden dimmed, staining with grey. Sanguinius wrestled with confusion, and he gripped the column. It cracked. ‘You said Imperium Secundus was not a sin.’

‘You are the source of the contradictions,’ the Emperor said. ‘I cannot speak except as you think I would.’

The column cracked again. Dust drifted to the ground. The breeze became a wind. Spray blew from the fountains. Their streams became erratic, splashing against the sides of the basins. Grinding came from the clockwork mechanisms. The planets shuddered in their revolutions. The reality of the cloister was eroding. It was turning to sand beneath Sanguinius’ fingers, eaten away by his disbelief.

‘You are a lie,’ he said to the Emperor. Uttering those words felt like falling on his sword.