how was this story ahead of its time?

In Pudd'nhead Wilson, Twain delivers a scathing critique of slavery and race relations in the American South. He highlights the arbitrariness of racial classifications and distinctions, by showing how easily Roxy (a slave) is able to switch her own child with her Master's offspring. The young, usurping slave grows up amongst whites without drawing any suspicions. Twain thus demonstrates how artificial and constructed racial distinctions truly are. These themes put into Twain's context Old South were definitely ahead of their time.