The paper discusses the intrinsic analytical differences and essential similarities of Kalecki and Keynes' analytical construct. It attempts to shed light on the fact that biographies matter in Keynes and Kalecki scientific contributions. Kalecki and Keynes are increasingly recognized as having permanent places in the pantheon of economic theory and political economy though interpretation and evaluation of their relative contributions is a controversial question. It is my contention that the basic issue is not one of priority of Kalecki's publication or the extent to which he anticipated Keynes' monumental General Theory but that in many respect Kalecki's conception and analytical construct and policy implications he derived there from are superior to that of Keynes. It is just as appropriate and useful to take Kalecki's construct as a criterion to judge Keynes' contributions as it is to Keynes' General Theory as a yardstick for measuring Kalecki's contributions. The paper concludes that Kalecki and Keynes Weltanschauung and theoretical differences undoubtedly colored their respective policy interpretations and prescriptions.