He understood the mechanism on the hundred and sixtieth day.
Not fully. The mechanism of a Strata sealing was not something a hundred and sixty days was sufficient for. But he understood the shape of it — the part that the original civilization had also understood: the shape, the direction, the place where the shape intersected with what he specifically was.
He understood it the way the Fate mark confirmed understanding: quietly, because everything before it had been pointing here.
★ ★ ★
The mechanism was this.
The Strata was not a wall. Walls failed through structural weakness — cracked, fell, were overwhelmed. The original sealing had not built a wall.
It had built a principle. A principle embodied by the ancient things through the conduit of the civilization's collective pact relationships.
Principles did not fail structurally. They failed when they were no longer embodied.
The Strata was failing because the ancient things that had embodied the sealing principle were no longer fully present in it. They were present at the withdrawal level — aware, monitoring, maintaining the relationship. But the full embodiment that the original sealing had required was not ongoing. It had been a single event. The single event had produced a self-sustaining principle, but self-sustaining principles eventually ran down without re-embodiment.
What was needed was not a new sealing. A re-embodiment. The same principle, the same ancient things, fully re-engaged rather than maintained at withdrawal distance.
The original civilization had produced this through collective full-expression contribution. Every pact relationship opened to full depth, simultaneously, the combined conduit sufficient for the ancient things to re-engage completely.
The cost had been dissolution. Dissolution was the cost of the full-expression opening, not the cost of the sealing itself.
The notation had said: they did not know there was an alternative.
The alternative: the full-expression opening did not have to dissolve the conduit if the conduit was configured to survive it. If the conduit had a principle of its own that was compatible with the force passing through it, the force could pass through without destroying the channel.
The Hollow Interval was the principle of the between. The between was the space where force passed from one state to another. Not accumulated, not held — passed through.
A vessel accumulated. A vessel held and was eventually overwhelmed by what it held.
He was not a vessel.
He was the between.
★ ★ ★
He sat with this for four hours. Then went to find Dreya.
He told her the mechanism. The distinction between wall and principle, between vessel and conduit. The between and what the Hollow Interval's nature meant.
She listened. When he finished she was quiet for a long time.
"You're saying you can survive it," she said.
"I'm saying the dissolution was the cost of a method that did not account for a conduit designed to let force pass through rather than hold it," he said. "I don't know if I can survive it. I know the reason the original civilization couldn't doesn't apply to my configuration."
"That's not the same as survivable."
"No," he agreed. "But it's a different question than I was asking forty days ago."
She looked at him. The Gaze read her structure: the sealed room was still sealed. The weight of him that had become load-bearing in her architecture was present at full weight. And the organized patience had a different quality — not the patience of someone waiting to see what emerged. The patience of someone who had already seen it and was sitting with what that meant.
"What do you need," she said.
"The Veil's pre-Strata research. Everything. Time to verify the mechanism through the ancient things' own framework — from their side, not mine." He paused. "And I need to tell the others."
"Yes," she said. "You do."
He looked at her for a moment. Something in the sealed room's structure had changed — not opened. Changed. The specific change of a sealed thing that had been examined from the inside and found to still be sealed and was, for the first time, considering whether it needed to remain so permanently.
He did not acknowledge it. He thought: she will get there when she gets there.
He went to tell the others