The "heroic theory of invention" stresses the role of individual geniuses in developing inventions. So we remember Alexander Graham Bell, Thomas Edison, James Watt and others as pioneers who brought forth their inventions from nothing. Diamond argues instead that inventors usually develop, adapt, or repurpose their inventions from previously existing technology. James Watt, for example, is remembered for inventing the steam engine, the inspiration for which he allegedly got by watching a teakettle boil. In reality, Watt developed his steam engine from a previously invented model by Thomas Newcomen, which was an adaptation of an engine developed by Thomas Savery, which had been inspired by earlier, European models. The point is that technology seldom develops in isolation, but rather by a process of adaptation and improvement.