I am extremely grateful to Jeff McDonnell for having led this nomination and for his very generous citation. I am also, of course, deeply honored by this award, particularly since I have the greatest respect for Robert Horton as perhaps the most important hydrologist of the twentieth century. Certainly as far as I know, he is the only hydrologist to have a waterfall named after him, near his home in Voorheesville, N. Y. That respect was deepened when a few years ago I had the opportunity to look over just a small selection of the 94 boxes of his papers in the National Archives. That showed that he had a much greater appreciation of the complexity of hydrological systems than he is given credit for in current textbooks. It is that complexity that I have struggled with throughout my career, complexity that is so poorly represented by the available measurement techniques and that makes hydrological prediction so difficult and shot through with epistemic uncertainties, i.e., uncertainties that arise from lack of knowledge rather than random natural variability. The GLUE methodology was mentioned in the citation. It is an on-going research program that tries to deal with uncertainty in nonideal real-world applications when simple statistical assumptions may not be enough.