The above quote from S.L. Louwes, which stems from his defence of his policies as leader of the RBVVO, makes clear why it is difficult to establish causal relations in historical epidemiology. The number of factors potentially contributing to disease or mortality regimes is almost literally endless. This poses a problem, of course, to any investigation of Dutch wartime mortality. As explained in Chapter 2, child and adolescent mortality increased significantly in the Netherlands in the years before September 1944, but not in Denmark. The standard of living in the two countries, which has been investigated in detail in the past five chapters, must in one or more ways have been so different that it can explain the divergent impact of occupation on public health. The comparative investigation of Denmark and the Netherlands offers a possible way out of the problem of identifying the causes of Dutch wartime mortality. Hitherto, as noted, rather generic explanations, not dissimilar to the ones given in the Louwes quote above, have dominated Dutch historiography. Lou de Jong, in his seminal history of the Netherlands during World War II, placed food shortages (of which he had little concrete understanding at the time) centre stage as the cause of declining health, alongside the cold, the mass movements of people and, especially, the loose wartime morals. In contrast, Trienekens and Klemann are much more optimistic about the wartime diet, but they too adhere to the image of a general decline in the material standard of living as the main cause of increased mortality in the Netherlands before the Hunger winter. However, these explanations do not differentiate quantitively between the various contributing factors. In the light of the previous four chapters, this is hardly satisfactory: many of the developments traditionally considered to explain the Dutch mortality regime clearly took place in Denmark as well, without having any such impact.