 As examples of the knowledge intuition, Stoljar &amp; Nagasawa cite passages by Bertrand Russell (1998, 13–14) and by J.W. Dunne (1929). As Dunne puts it, quoting James Ward, physical descriptions cannot entail knowledge of what it is that “you immediately experience when you look at a field poppy” (1929, 5). Around the same time as Dunne was writing, C.D. Broad (1925) used a thought-experiment as part of an argument against a mechanistic version of physicalism. Broad argues that even if the mechanistic theory of chemistry were true there still would be a property of ammonia that a mathematical archangel endowed with unlimited mathematical skills and “gifted with the further power of perceiving the microscopic structure of atoms” could not predict, namely its smell: