The extensive use of Betrand Russels great but very personal history of philosophy as a source is probably to blame The article should have a section with criticism of Democritus and the whole idealist vs materialist discussion could be outlined here An encyclopaedia article do not need an conclusion Instead of a lot of assumptions of the superiority of mechanistic thinking there could be a section with influences all materialists  Hobbes Marx John Dalton for the atom  and maybe it seems  Russel