Book design is a practice in subtlety. Careful attention is paid to the proportions of the margins, indentation, and numbering. The leading (line spacing) can determine how quickly a page is read, as well as how comfortable the reader's eye feels while reading. And the choice of font can have a significant impact on the pacing, and even the mood of the read.
All chapters begin on the recto (front side, or right-hand page). Ornamentation on a page can be an engaging accent, or an imposing distraction. The floral elements on the verso and in the margins are intended to be a visual counterpoint to the text, and only slightly less visually prominent.
The range of decoration accommodated by a codex page is broad - contrast the above image with any page from the Kelmscott Press.