In Chapter 21 of To Kill a Mockingbird, Harper Lee portrays the contrast between the idealistic thinking of the boy Jem and the realistic reasoning of his father. First of all, after Mr. Underwood tells Atticus,
They're right up yonder in the colored balcony--been there since precisely one-eighteen P.M.
Atticus is upset that the children have heard all the testimony by being in the courtroom, so he calls to his son, "Jem, come down from there." As the children approach, Calpurnia looks "peeved," Atticus "exhausted."
Then, the idealistic Jem, "jumping in excitement," does not notice the weariness of his father, or the exasperation of Calpurnia as he exclaims, "We've won, haven't we?" Nor does he understand Atticus's curtness:
'I've no idea,' said Atticus shortly. 'You've been here all afternoon? Go home with Capurnia and get your supper--and stay home.'
But, Atticus relents and allows the children to return after eating supper "slowly."