It should by now be evident that tradition, the handing on of the achievements of the past, plays an all-important part in the formulation of a theory of natural law. For this reason Isidore of Seville has an importance out of all proportion to his personal achievement in that he preserved so much of antiquity. An excellent example of use made of materials so preserved is found in the twelfth century canonist Gratian. The influence of Isidore upon Gratian is palpable in the matter of the natural law; and Gratian and his commentators were to influence the theologians of the High Middle Age.¹