Throughout the 20th century, an impressive amount of scholarship was devoted to the origin of the concepts of the prince and sovereignty. By focusing on the ancient and mediaeval sources of 16th-century authors, I tried to determine the degree to which the modern fate of the notion of power depended on ancient and mediaeval debates. I paid special attention to the ethical, anthropological, and legal questions implied in the European encounter with the ‘New World’. Despite its broad relevance to studies on early modern era, this subject has often been disregarded with respect to the history of the concept of power. My analysis helped me trace this subject within the most central debates of the last decades of the 16th century. Through the authors of this time, I showed the interrelation between the discussion on Native Americans and a variety of sources of modern history of ideas, which span early-modern philosophy, cosmology, theology, and public and international law.