These two pages show a change of chapter. At the end of each chapter the text becomes funnel-shaped so you know that you are at the end of a chapter. The first letter of the paragraph of the new chapter then is very decorated and much bigger than the others. I took this pair of pages because it shows a very effective way to illustrate the change of chapters.
Those two pages are both the start of a chapter. You can see that the first letter of the left side page is much more detailed than the first letter of the right side page. Also they both have a drawing which is filling most of the page.
The first page of this pair is filled with a drawing and there are a lot of letters but no legend where it explains all these points, which seems to be strange. The page on the right side shows the drawing from another angle and with hatching. It seems that the text then explains the relation between the letters in the drawing. I choose this pair of pages because the construction looks interesting.