In my study, The Natural Law Tradition and the Theory of International Relations, reviewed in Hedley Bull's interesting article, there are no chapters devoted to natural law thinkers before the thirteenth century. Any lengthening of an already long manuscript might have diminished its prospects of publication. In the absence of a full survey of the strengths and weaknesses of earlier theories, there are various explicit or implied judgements on positions of Aristotle, the Stoics, Cicero and Augustine in chapters dealing primarily with other matters. Whilst referring to sources of Aquinas's doctrine, I did not give a detailed account of the historical formation of his teaching. I concentrated upon St. Thomas's discussion of the various kinds of law and especially upon the doctrine of eternal law which he brought to a certain perfection. In doing this, I was consoled by the view which I shared with Vincent McNabb that “it was always the thought of Aquinas never the history of that thought which seemed of greatest worth…” Indeed, given the incompleteness of so much of the discussion on the intellectual reconciliation of natural and divine law before Aquinas, it is arguable that McNabb was hardly exaggerating very greatly when he wrote that Aquinas's treatise on law in the Summa theologiae “would seem be the first great treatise ever written on law”.
