David Herbert Fowler (/ˈfaʊlər/; April 28, 1937 – April 13, 2004) was a historian of Greek mathematics who published work on pre-Eudoxian ratio theory (using the process he called anthyphairesis). He disputed the standard story ofGreek mathematical discovery, in which the discovery of the phenomenon of incommensurability came as a shock.His thesis was that, not having the real numbers, nor division, the Greeks faced difficulties in defining rigorously the notion of ratio.