Indeed, you could subject headings as acting within the catalog not unlike hyperlinks do on the Internet. Let's consider the record a bit more. It is attempting to represent a book as portrait, photograph, a sculpture, a biography of a person is an attempt to represent that person. This may seem an odd thing to say. For the record doesn't resemble a book the way that a photograph of a person resembles a person.
Photographs are two dimensional, people are three dimensional.
Photographs are composed of chemically treated paper exposed to light. People are composed of cells. I could go on. Same for paintings. For instance, the Location field in the record above tells us this book is located, broadly speaking, in Middleton Library.