The essays in the first part of the volume provide a careful analysis of the varied meanings of the word ‘right’ (ius) in moral philosophical and political sources already at beginning from the fourteenth century. However, whereas the late medieval scholars developed merely the language of a subjectively understood rights language, the early modern scholars created the first theories of natural rights on that basis. The essays in the second part of the volume focus on the philosophically and politically significant aspects of natural rights, with particular reference to the themes of natural equality, justice and action in early modern context.