This article is based on a talk that was given by the author at the Institute of Historical Research on 3 February 2011, on the Victorian polymath Francis Galton and the malign legacy of his eugenic theories. It pays tribute to the pioneering work of the late Brian Simon in challenging the whole idea of "fixed innate intelligence" and in furthermore insisting that a belief in "human educability" should be at the heart of the campaign for comprehensive education.