The most important theme of this powerful account of life as a female slave is the inhumanity of slavery. Jacobs takes great pains to ensure that those who practise slavery cannot be viewed as benevolent in anyway, as she argues that slavery is so toxic it ruins the sense of right and wrong that those who own slaves have. The complete and total power that slave owners have result in their unrestrained behaviour with no legal barriers or censure. This can be seen in those owners who are depicted as better than others, such as Mr. Sands. Note the way that he promises to free his children, but yet during a time of financial hardship the temptation to sell them and profit through their sale is too great.
Of course, it is not just slave owners who suffer from slavery, and much of Jacobs' narrative concerns the impact of slavery on the slaves themselves. One of the recurring themes of this account is the way that slavery is worse for women than for men, as Jacobs says:
Slavery is terrible for men; but it is far more terrible for women. Superadded to the burden common to all, they have wrongs, and sufferings, and mortifications peculiarly their own.
This is of course highlighted by one of the most powerful passages in the book when Jacobs reveals how she consented to have sex with her master. She states that unless a woman has occupied the same hardships and position of having no power as she has, they are not able to judge her. For the slaves, Jacobs argues, slavery is damaging because it prevents them from fully developing as humans.