With a will, determination, selflessness and devotion for which words are too weak, she consecrated her whole life and her whole being to Socialism. She gave herself completely to the cause of Socialism, not only in her tragic death, but throughout her whole life, daily and hourly, through the struggles of many years ... She was the sharp sword, the living flame of revolution.
source
Clara Zetkin, her closest friend, as quoted in Rosa Luxemburg, Ideas in Action (1972) by Paul Frölich, p. x