“Logic is also the theory of knowledge of Marxism, but for quite another reason, because the forms themselves of the activity of the ‘spirit’ – the categories and schemas of logic – are inferred from investigation of the history of humanity’s knowledge and practice, i.e. from the process in the course of which thinking man (or rather humanity) cognises and transforms the material world. From that standpoint logic also cannot be anything else than a theory explaining the universal schemas of the development of knowledge and of the material world by social man.”