Hate must make a man productive. Otherwise one might as well love.

The aphorism turns hatred into a kind of moral and intellectual test. Kraus implies that if one is going to indulge a destructive passion like hate, it should at least be harnessed toward concrete work—exposure, critique, reform, or art—rather than remaining sterile resentment. The sting of the closing clause (“Otherwise one might as well love”) is that love, conventionally seen as the more generous emotion, is here presented as at least equally “useful” unless hate can justify itself by producing something. In Kraus’s satirical worldview, emotions are judged by their consequences: unproductive hate is merely another form of self-indulgence.