Examine what the price of freedom is for Isabel.
Isabel pays a high emotional and physical price for freedom. When she remarks to Curzon at the end of the book that she thinks that they "have crossed the River Jordan," she does so at an amazing price. Isabel has been separated from her family. The emotional network that she relied upon in terms of family members such as a sister and mother have had to put aside in her quest for freedom. The hallucination she has of them in the final sequence is reflective of how emotionally estranged she is. The institution of slavery forged that separation. However, the desire for freedom was an individualistic one for her, something that was to be endured without any remnant of the emotional network that could care for her. The need to find freedom has come at the cost of others joining her on her quest.
Physically, Isabel has paid the most intense of prices. The blisters that form and open up on her hands as she rows herself and Curzon to freedom is one example of this. Additionally, Isabel has endured much abuse, starvation, and physical endurance on her road to freedom. When she makes it, she is physically weakened, but still is able to walk on her own, asking Curzon if he is able to walk on his own. This weakened state, but a condition that still compels her to look out for another is a reflection of how much she has sacrificed physically for her freedom.