She had a taxonomy. It had taken her until her late twenties to develop it and another ten years to refine it to the point where it was genuinely useful. The taxonomy had three levels, which corresponded roughly to depth of access rather than intensity of experience, though the two were often correlated.
Level 1 was ambient residue: a faint pressure that was mostly emotional in character, unreliable for specific information, and often not her own. You could feel Level 1 in certain hotel rooms, in corridors, in the carriages of old trains. It was pervasive and she largely ignored it, the way you ignore background noise in a city you have lived in for years.
Level 2 was structural: something from her own past, genuinely accessible. This was the level that required attention. When it came, it came with specific content, a particular quality of experience from some time in her life, present in the way that a person standing in the room was present. She had learned to sit with it rather than react to it. She had a notebook for it.
Level 3 was historical presence: something from before her, happening in a space. She had learned to distinguish this from Level 2 by the quality of the experience, which had a density and strangeness that her own memories did not. Level 3 was old. It had specificity without personal recognition, the way you might recognize a skill without knowing where you learned it.
She was at a train station, a large one, and she was getting a Level 3. It had started in the main hall and was still present, strong, as she walked toward the platforms. The station was over a hundred years old. What she could access was not visual, not auditory. It was a quality of weight: collective urgency, many people moving through this space with something important ahead of them. Not fear. Urgency had a different register from fear, more directed. Whatever this had been, it had happened here with frequency, and it had accumulated in the walls and the floors until it was accessible to someone like her who paid attention.
She had twelve minutes. She pressed her hand to the wall near one of the pillars. Cold tile, slightly gritty. The contact did not intensify the access, but it helped her remain present to it without losing herself in it. She had learned this in her thirties. Touch helped.
She got out her notebook and wrote: "Station. L3. Old, possibly wartime-adjacent or migration-period, collective urgency without fear, very high density, structural not episodic." She added the date and time. She had 201 Level 3 entries in the current notebook and four full notebooks before that.
She boarded the train. Through the window, the platform receded. The station's presence was still perceptible at two hundred meters, faint, like a sound you're not sure you're still hearing. She did not turn from the window until it was gone.