Through all of time, there were always people who thought slavery was wrong. It has to with our genetics as primates; as an example, even in chimpanzee groups murder (infanticide) happens occasionally, leading to great stress and panic in the group, indicating that on a basic level the primates (as social animals) know it is simply wrong (it is encoded in our genetics). Discussions about morality appear at that exact moment where the hard-coded gets into conflict with the harsh reality of suppression, egoism and social action. Thus, throughout time, when humans acted against our basic altruistic instincts, there were always people who raised their voice against violence, claiming that these actions were “immoral”. Alas, humans have a great capacity to gloss over wrongdoing, as we are also strongly egotistic, and we can actively suppress our altruistic characteristics.