To Kill A Mockingbird
This is a sophisticated question. In chapter 25, Scout does learn about the "secret court of a man's heart." Her meaning is twofold.
First, she realized that people were racist. No amount of evidence was going to free Tom Robinson. No matter how brilliant Atticus was, he was going to lose in the hearts of men, because no black man would win over a white woman's words. Here is what Scout says:
Then Mr. Underwood’s meaning became clear: Atticus had used every tool available to free men to save Tom Robinson, but in the secret courts of men’s hearts Atticus had no case. Tom was a dead man the minute Mayella Ewell opened her mouth and screamed.
Second, Scout learned that the people of Maycomb were shallow and vacuous. They really did not care about blacks. Life and death were not things they thought about too much, when it came to a black man. At best, Tom Robinson's death (and life) was a temporary diversion. In their hearts, they could care less.
Maycomb was interested by the news of Tom’s death for perhaps two days; two days was enough for the information to spread through the county. “Did you hear about?... No? Well, they say he was runnin‘ fit to beat lightnin’...” To Maycomb, Tom’s death was typical. Typical of a nigger to cut and run. Typical of a nigger’s mentality to have no plan, no thought for the future, just run blind first chance he saw.