Perspective is an interesting subject, the basics are condensed as "Things farther away from you are smaller and things closer are bigger."
If you have never studied perspective, drop what you're doing right now and learn about basic perspective from somewhere first.
My explanation of page 30:
Take out a blank sheet of paper. Hold it up with the flat side facing you with the side touching the table. Imagine a little man smaller than that paper climbing onto the table. He stands facing you with his back touching the paper you are holding up. Suddenly a paint bomb drops from the ceiling and explodes in front of the little man. The little man gets scared and runs away. You are more interested in perspective than the little man so you look at the paper you are still holding up. The paper is now covered with paint except for the exact area where the little man used to be blocking the paint with his body. This area on the paper not covered in paint is the flat diagram of the figure that page 30 describes. The scene of the crime. Look at the flat diagram and let that information sink in for a bit.
Now take out two identical books and put them next to each other side by side. Let one book stand up on the table with the cover facing you and the other book lie back flat onto the table. Take a picture of this scene with a camera pointing absolutely straight ahead at the wall in front while capturing both books. Examine the picture and compare the two books in the picture. Do they "look" the same to you in the picture? If they do, here's a simple proof that proves otherwise. They do not "look" the same in the picture at all because you can tell that one book is laying down and the other book is standing up. If both books "looked" the same in the picture, there would only be one book in the picture. This holds true even if the books were both standing up or both laying down. These differences on how they "look" different in the picture even if they are identical objects is part of what perspective explains. What one draws onto paper is like what the picture the camera takes and if you have x-ray vision, the backcover of the book is like the flat diagram. The basic concept of page 30 is one can map proportions of humans into space.
Anyways if one wants to know anything specific about perspective, ask.
If there is something unclear about my explanation I can clarify.
Also I remind to drop what you're doing right now to learn basic perspective because it is very important to drawing.
I highly recommend "Perspective Made Easy" by Ernest Norling because perspective is made easy
Last edited by fiftyeightsqq
on Sun Sep 20, 2015 5:06 pm, edited 1 time in total.