Part 1 — THIS WORLD

Section 1. — Of the Nature of Flatland

Section 2. — Of the Climate and Houses in Flatland

Section 3. — Concerning the Inhabitants of Flatland

Section 4. — Concerning the Women

Section 5. — Of our Methods of Recognizing one another

Section 6. — Of Recognition by Sight

Section 7. — Concerning Irreglular Figures

Section 8. — Of the Ancient Practice of Painting

Section 9. — Of the Universal Colour Bill

Section 10. — Of the Suppression of the Chromatic Sedition

Section 11. — Concerning our Priests

Section 12. — Of the Doctrine of our Priests

PART II — OTHER WORLDS

“O brave new worlds, That have such people in them!”

Section 13. — How I had a Vision of Lineland

Section 14. — How I vainly tried to explain the nature of Flatland

Section 15. — Concerning a Stranger from Spaceland

Section 16. — How the Stranger vainly endeavoured to reveal to me in words the mysteries of Spaceland

Section 17. — How the Sphere, having in vain tried words, resorted to deeds

Section 18. — How I came to Spaceland, and what I saw there

Section 19. — How, though the Sphere shewed me other mysteries of Spaceland, I still desire more; and what came of it

Section 20. — How the Sphere encouraged me in a Vision.

Section 21. — How I tried to teach the Theory of Three Dimensions to my Grandson, and with what success

Section 22. — How I then tried to diffuse the Theory of Three Dimensions by other means, and of the result

Source - http://xahlee.org/flatland/

this explains the 22 sections of the book in both parts...

this can be used very effectively in my idea as "Flatland by Edwin A Abbott" contains 22 characters allowing for an origami letter for each section!