The Painted Cave

The fourth book by V. M. Straka, published in 1919.

It displays an evolution of style turning towards methodical and meticulous writing, it became one of his most successful books.

It has similarities with Amarante Durand's All of This to You I Give, and some of the archeological details must have come from her. It displays detailed knowledge of archaeological sites in the south of France, specifically the painted walls in Valojoulx which Durand discovered. However the descriptions match perfectly the famed Lascaux cave, which was discovered 20 years after the book was published.

According to FXC, perhaps in a deliberate lie, she translated it. In one of his letters Straka said to her that an unseen hand guided him and showed him the story.

Contents
It describes a cave, in which there are symmetrically arranged stalactites, resembling organ-pipes.

In pp. 48-55 there are descriptions of several symbols, some of which reappear in Ship of Theseus Ch. 7

P. 144 contains the phrase "ancient geometries".

Generally, the chapter 5 of SoT seem to draw from that book.