The concepts of mass and energy are extremely useful physical quantities. The study of these physical quantities has started since days of Aristotle or even before. G. Corolis made a significant breakthrough by defining work as W=F.S = FScos theta and derived kinetic energy equal to mv 2 /2. Newton initiated the discussion on inter-conversion of mass and light energy. Then various scientists such as S. Tolver Preston, Jules Henri Poincar?, Olinto De Pretto, Fritz Hasenohrl, Frederick Soddi, derived equation for inter conversion of energy before Einstein. Some of the scientists, who did significant work in this regard are least known. Then Einstein in 1905, derived light energy-mass equation (L = Dmc 2) about which Newton had mentioned about two centuries before. Further from L = Dmc 2 Einstein speculated more general equation without any specific derivation = Dmc 2.
Keywords: Mass, Energy, Aristotle, Einstein