This article aims at sketching the prima facie “paradoxical” legal status of “slaves” in Roman law. Hence, it deals with principles and rules directed to regulate two paradigmatic and highly relevant areas of economic life, i.e. sale and agency. Both shared the fundamental presence of servi or mancipia, conceived at times as mere objects, at times as real individuals. On the one hand, according to non-Roman conceptions (that consider slavery per se a liminal and, thereby, indefinable institution), the law concerning serviles personae would represent such a contradiction by merging the Aristotelian categories of bios and zoe. On the other hand, pre-classical and classical Roman law, adhering to a functional and wide notion of legal persona, and embodying a status-system, transcends any apparent inconsistency between property law and business law.