This book offers an in-depth examination of constituent power through the writings of six major philosophers from the 16th and 17th centuries, highlighting how their ideas have shaped the foundation and transformation of political philosophy. Filippo Del Lucchese delves into how La Boétie, Bodin, Lipsius, Campanella, Suárez and Hobbes conceptualized and influenced the evolution of this fundamental political idea. By examining their writings, he illuminates the diverse interpretations and the profound impact these thinkers had on the formation of political authority and constitutional frameworks. He also bridges this historical analysis with contemporary debates on democracy, sovereignty and the enduring tension between political foundation and institutional stability in modern legal and political theory.