This article delves into the fundamental principles of conservation of mass and energy, tracing their historical development and exploring their application across various phenomena. The author meticulously examines both concepts, illustrating the conservation of mass through a classic chemistry experiment. For conservation of energy, Armstrong offers a refined definition related to work and then demonstrates its persistence by analyzing the interconversion of potential and kinetic energy. Ultimately, the piece argues that even in nuclear reactions, mass and energy are conserved separately but appear linked through radiation, where a specific amount of mass accompanies a corresponding amount of energy, as dictated by the theory of relativity.