That external factors have an impact on the law is obvious enough: we have studied in some detail how the cultural climate in twelfth-century Europe led to the rebirth of ancient Roman jurisprudence and how, in nineteenth- and twentieth-century Germany, political concerns and patriotic passion were focused on the Civil Code. It would, however, be a mistake to underrate the internal logic that operates within legal systems and determines their progress independently of cultural fashion or political pressure. Generations of civilians distilled their concepts and norms from authoritative premises by applying the rules of logic. Thus we can trace the continuous refinement of the notion of tort through a span of more than two thousand years, from the Lex aquilia to art. 1382 of the Code civil. Similarly, English judges patiently formulated, in the course of many centuries, certain fundamental norms on the strength of precedents and obiter dicta handed down by their predecessors; those judges applied the eternal equitable and reasonable principles of the common law to the cases before them, irrespective of the commotions and upheavals that raged outside the sacred halls of their courts.

Whether external events or internal logic is more important for the development of the law is a moot point. It reminds us of the discussion that separates the ‘reductionists’ from the ‘autonomists’ in the history of science.