Pufendorf makes a clear distinction between the physical constitution of human beings and their value as human beings, stressing that the latter is justified exclusively by the regular use of the free will.According to Pufendorf, the regular use of free will requires certain inventions (divine as well as human) imposed on the free will and called moral entities. He claims that these inventions determine the moral quality of a human being as well as the standards according to which human beings and their actions are able to be judged. This article examines the normative aspects of Pufendorf's concepts of moral value and moral estimation in regard to the epistemological question of the accessibility of moral entities for human beings. In the first part, it reconstructs Pufendorf's doctrine of moral entities and the place of moral estimation in this doctrine. In the second part, it presents Pufendorf's account of the moral philosophy as a science in order to explain his theory of moral normativity as imposed, and the role of a person in regard to their own moral status. In the last part, it illustrates some consequences in regard to the problem of slavery in Pufendorf.