here but there are always more details:
of the two globes on the desk, one is celestial, the other terrestrial showing places like Atlantis and Huy Braseal;
the bookshelves have Sokolnikoff's Introduction to Paratemporal Mathematics and the Handbook of Alchemy and Metaphysics;
Valeria, who has her own copy of the Handbook, knows theorems that enable her to travel to a particular continuum or one like it;
she even found the Old Phoenix by deducing that there had to be an interuniversal nexus;
by contrast, Holger travels randomly, using a medieval grimoire;
Valeria can teach Holger some of what she knows but he will be unable to use the knowledge unless he can prove and understand the theorems;
meanwhile, one of their fellow guests is a regular called Clodia Pulcher.