This will be fairly easy to find because it represents the essence of Douglass' case against slavery. Look for moments when Douglass describes the harshly physical treatment of slaves. Pay attention to how Douglass articulates how physical force was used to subjugate, control, and subdue slaves. This could also extend to the weapons or tools used to do this, such as whips or chains or shackles. I would examine the portion of the text when Douglass is sent to live with Covey and how "the slave breaker" uses wonton force to accomplish his goal. On a side note, the term "slave breaker" or "breaking slaves" might be another example of the physical nature of slavery, indicating its propensity for physical violence.