How we know / What we know

Dear all,

For this article, it is so hard to understand for me. However, I can get something from the article by examples. I think I can understand but it’s not clear. Therefore, I would like someone explain it to me.

The authors talk about levels of abstraction that influence to the reader’s understanding. Moreover, they explain about the step as “Abstraction Ladder”, but I don’t know the word “Bessie”, what dose it means? Is it the name that represents something? As for the other examples, I can understand about the process of abstracting which help both of the writer and the readers to communicate between them.

I apologize for my confusion.

Thanks
Best Regards
Jib