ABSTRACT
Quantum mechanics, as it is taught in various undergraduate courses, typically focuses on developing the formalism using the phase space or the Hamiltonian description of classical mechanics. This gives an impression to the student that Lagrangians cannot be used to develop a formalism of quantum mechanics. Of course, this is not true. Dirac is credited with originating the idea of the path integral in physics. However, it was Feynman who popularized this idea and made it widely accessible to physicists.
