The main topic of this article is the genealogy of the concept of the rule of law since ancient times until the late Middle Ages. It presents conceptions originating from legislative texts, juridical literature and philosophical writings (especially of Plato, Aristotle, Cicero, John of Salisbury and Aquinas) in order to show that in ancient and medieval times it was firmly accepted that arbitrary power shall be limited by law, in other words the idea of binding character of law for the ruler or “state”. In conclusion it describes fundamental differences between ancient and medieval conceptions of the rule of law on the one hand and modern conceptions. However, the conclusion emphasizes that many ancient and medieval ideas concerning rule of law were influential even in modern times and have been reinterpreted in new contexts.