The willow tree and Abra's secret

The twins enter the seventh grade at the West End school, under the picture of Laocoön wrapped in snakes. Cal works out a system of raising and withholding his hand until the teacher stops calling on them, and corners the schoolyard's marbles. He is respected and feared and has no friends; Aron, pretty and slow and a dogged fighter when crying, draws love from every side. Aron follows Abra home to a house of leaves under a willow by the pump house, where they agree to be husband and wife in practice. She plays his mother, and he weeps in her lap without knowing why. Then she tests him for a secret, and when he refuses to give one up she tells him hers: overheard in the buggy, that his mother is not dead but went away. Alone under the willow, Aron comes at last to the big piece — if his mother is alive, his father is a liar, and Lee, who built Adam as the foundation of truth, is one too. He pushes his mother back into death and goes in late to supper.

Lee's argument against lying to the boys is collected here, years later, as a bill: Aron cannot hold both his father's honesty and his mother's existence, so one has to be killed. The willow scene does the setting-up, so the choice costs something the reader has watched him want. His "Good night, Father" is the whole decision, said to a man who notices nothing.