They are angry because they know they deserve fair treatment, even though they are treated unfairly.
In order for them to access their power, they must acknowledge their own anger, which is the seed that contains the truth of their experience.
Even the fate of the pets is contrasted, since in the black families, pets seem to meet a cruel fate (witness the cat killed by Junior and the dog cruelly poisoned by Soaphead Church).
The reader is repeatedly reminded of the backdrop of white, Anglo cultural values that act on the characters.
The clearest example of this is when Pauline comforts the little white daughter of her employers but denies her own daughter affection or comfort.
Then when Pecola becomes mentally unbalanced, her mother will not even speak to her.
Reduced to unpunctuated lines and fragments, this passage is repeated many times as a heading for various sections in the novel.
The effect is to contrast the idealized white family with the reality of several black families, especially Pecola's.
The Effect of White, Anglo Cultural Values on Non-White People The novel opens with a passage from a 1940s reader in which the ideal, white family is depicted.
The family lives in a green and white house and consists of a mother, a father, a son and a daughter, and a pet dog and cat.