Philosophical idealism is only nonsense from the standpoint of crude, simple, metaphysical materialism. From the standpoint of dialectical materialism, on the other hand, philosophical idealism is a one-sided, exaggerated, development (inflation, distension) of one of the features, aspects, facets of knowledge, into an absolute, divorced from matter, from nature, apotheosised. - Lenin, Summary of Dialectics (1914)