Kosambi was a scientist who talked about the past with the politics of intimacy with the present. This paper identifies the "Kosambi effect" and its various constituents. The most crucial constituent is the awareness that historical knowledge cannot be based on empirical givens and that a methodology guaranteeing a systematic, deductively formulated, and empirically verified concept of reality about the past is indispensable. The adaptation of historical materialism to serve the purpose, and accordingly writing a history worth designating a genre by itself in form, content and hermeneutics is another crucial constituent.