  Although the mind cannot direct the creation of ideas, it can direct the selection of them. Selection occurs when the scientists choose the theories, out of the pool of available variation, which best fit the data and other pre-existing ideas. It is also worth noting that Mach talks of the tendency for resistance to change as being both necessary and problematic for science. Mach was not only one of the founders of Gestalt Theory, but also applied its core concepts to the process of science. Packaged together with his use of history to elucidate science, he anticipates Kuhn’s ideas on scientific change and progressive rationality.