The diagrams seem to refer to some kind of spiritual energy sequences - they're hard to understand without the complete context. As Lapis moves on through the journals, she'll discover that the written journals seem to end somewhere around the 1950's... did she move to a different format?

She never gets the chance to check, because it's while she's bent over snooping through those books that Lesedi Santiago will soundlessly enter - only to make a soft sound of surprise at discovering that she's not alone. A look of surprise that swiftly twists into something malevolent.

"It's you," she says, wounded and victorious all at once.