Paolo Prodi's clearly and transparently written book is a masterpiece of political idea history and interdisciplinary scholarship. It not only provides a solid historical overview of the development of the concept of justice but also delivers the intellectual background against which current debates about conscience and law can be better understood in all their complexity and scope. Paolo Prodi outlines an impressive and extensive panorama of ideas about justice, ranging from the Old Testament and Greek antiquity to the present day. The starting point is the religiously influenced understanding of iustitia, according to which justice between people and God's justice are closely interconnected. However, from the 13th century onwards, a pluralism of legal systems gradually emerges.