This article has the modest task of introducing non-Bulgarian readers to some of the leading themes and achievements of Evgeni Mateev, especially the evolution of his views towards systems theory and cybernetics, and his model of decentralised democratic planification and socialism and the algorithm for its application. We offer some methodological points from the author's model, developed in his last fundamental work from 1987 Structure and Management of the Economic System. The author's theoretical vision of the technological and cybernetic possibilities of systematising and managing huge information flows and the ongoing management of various hierarchical levels, is particularly relevant today in light of the development of modern information and digital technologies, artificial intelligence, etc. We have tried to stick to an objective presentation of the author's work, keeping normative judgements to a minimum.