They all broke the rules. They all crossed into forbidden territory. They all tampered with the laws that lay down who should be loved and how. And how much.
-- Narrator (Chapter 1 paragraph 188)

Importance: This quote identifies the strict rules of the caste. The rules were very strict in not loving or marrying "down." However, everyone was guilty of breaking the rules when it came to love.

In those early amorphous years when memory had only just begun, when life was full of Beginnings and no Ends, and Everything was Forever, Esthappen and Rahel thought of themselves together as Me, and separately, individually, as We or Us. (Chapter 1 paragraph 9)

Importance: Rahel and Estha are "two-egg twins," fraternal twins. Until they are separated after the death of Sophie Mol, they consider themselves to be one person. They experience the world in a way that gives the impression they know what the other is thinking and has experienced without words...