"Bliss was it in that dawn to be alive, but to be young was very heaven!" English poet William Wordsworth's reaction to the fall of the Bastille in 1789 conveys the exhilaration of those precious moments when the masses overthrow an old society and build a fresh one.
Such events must be distinguished from superficial change. Under capitalism there is a constant turnover of rulers, technology, family structures and ideas. The microchip has superceded the spinning jenny; Barack Obama follows George Bush; even the banks are nationalised - but capitalism continues. Revolution means change at the most fundamental level. States are transformed, ruling classes are replaced by new ones, production and distribution are radically altered. Nothing stays the same.