Card is an extremely good writer, and his books are always a pleasure to read, but at times I did feel that the stories here occasionally suffered for being too allegorical, and too much about Card's ideas of morality.
With the 3rd book in this series, 'Prentice Alvin' the focus shifts to an anti-slavery topic. (The second dealt more with the treatment of Native Americans by colonists). Here, we meet Arthur Stuart, an orphaned black slave whose mother dies magically getting him to freedom. Slave hunters come seeking the boy, and Alvin must use his 'knack' to help him escape. Also, a new school teacher arrives in town, disguised, because she is the future-seeing 'torch' who saved Alvin's life when he was born, and is afraid of the destinies she sees for herself with him.