This is a reprint of chapters 4–5 of The Medieval Polish Doctrine of the Laws of Nations: Ius Gentium by Stanisław Wielgus (Lublin: Redakcja Wydawnictw Katolickiego Uniwersytetu Lubelskiego, 1998), 55–101. The original chapter and section numbering has been retained, but footnote numbers have been adapted. Reprinted with the Author’s permission. In attempting to summarize in a few sentences the achievements of the medieval scholars of the Polish school of ius gentium, we must emphasize that by employing the inherited legal and (...) philosophico-theological tradition and intellectual achievements of the University of Kraków, coupling it with their own genius, they manager to create a coherent and universal system of international law. It was a system so modern, wise, tolerant and universal that it was able to be applied not only in solving the painful problem stemming from the lengthy conflict between Poland and the Teutonic Knights but was also used in resolving global problems of the contemporary Christian’s world conflict with the non-Christian one. That legal system, based upon the eternal principles of Divine and natural law, taking account of the Gospel Law of Love and inseparably connecting law with morality and justice with truth, remains valid even today. (shrink)