According to von Kármán a scientist seeks to understand what is; an engineer, to create what never was. But dichotomies are seldom clear-cut. When a scientist proposes a truly new hypothesis about, say, the origin of the universe, that hypothesis "never was" prior to its articulation by that scientist. Einstein, certainly a prototypical scientist, took that view, criticizing physicist and philosopher Ernst Mach for having "thought that somehow theories arise by means of discovery rather than invention." Science historian Thomas P. Hughes notes that to Einstein, invention was the manipulation not only of things but also of concepts. Einstein believed that an artifact was a materialized concept and that a hard-and-fast line between technology and science simply did not exist.