There are two ways in which to look at McLaurin's book; the first, is as the story of one particular slave, the second, as the story of every young female slave whose voice was never heard, and who did not finally take matters into their own hands the way that Celia did.
Although the author spends a great deal of the book explaining the different acts of government, political debate and opposing groups and the conflicts, the main takeaway from it is that slavery was a convenient vehicle for child sex trafficking. Celia, merely fourteen years old at the time of her sale to her master, was bought entirely for the purposes of sex. Newsom, missing the company of his wife and having physical needs that he wanted to fulfill, did not want to go to the trouble of finding a woman of legal age, so instead he chose to find himself a slave; propriety being important to him, he hid this by pretending that Celia was the possession of his young daughters. After all, it would hardly be appropriate for his girls to have a male slave, and an older woman would likely be more of a housekeeper than an assistant to two teenagers. It would seem perfectly proper to the onlooker for a young girl to be the slave to young girls.
It is very unlikely that Celia was the only young woman experiencing this. Girls with little or no documented history, no family to fight or look for them, and no actual rights of their own, were easy prey for men like Newsom, who knew that they could rape their slaves without ever having to worry about being reported to authorities, or killed in self defense, which was permitted in Missouri law at the time. The fact that the trade in young girls was disguised as the more standard practice of the slave trade is also another factor that reminds us of today's sex traffickers as well, as the modern day owners of sex slaves bring in girls with no traceable family or history of their own. Such was the case with Celia.
The sexploitation of young slaves was also enabled by the complete lack of laws to protect them, despite the best efforts of decent men like Jameson, her attorney. Although women were allowed to defend their honor using any means necessary, slaves were not considered people in their own right, but possessions, and a man can do whatever he wants with his possessions. Newsom would know that if he forced himself onto a young girl in the normal scheme of things he would be in deep legal trouble, or quite possibly injured if the girl decided to defend herself. He had no such worries with Celia.