Missionary societies operating in mid-to late-nineteenth-century Africa sought first and foremost to convert African men and women to Christianity. Among the assumptions held by European missionaries was the inherent sinfulness of the long-standing universal institution of slavery and the practice of human sacrifice. Slavery remained a general phenomenon in mid- to late-nineteenth-century Africa and was widely condemned by missionary workers. European religious workers simply did not have the power to prohibit the continued existence of these practices in the communities where they worked. They were guests who could exhort and attempt to persuade, but they had little power to force their values upon their hosts. They did use the power of the pen to condemn these and other practices and to publicize their existence in publications read by audiences in Europe. Missionary records are especially useful for hearing the voices of the enslaved.