ABSTRACT
Not only the Maxwell equations themselves but also all related conservation laws have been expressed with the help of two key observables describing the microscopic electromagnetic field, namely E and B. Strictly speaking, all relevant physics involving electromagnetic phenomena can be described correctly and completely in terms of the variables E and B solely, and from this point of view there is absolutely no need of defining auxiliary potentials akin to E and B. While the Maxwell equations are the starting point in the so-called inductive approach, one may alternatively adopt the deductive approach and try to “derive” the Maxwell equations from a proper variational principle. As a matter of fact it is possible indeed to postulate a Lagrangian density and an action functional such that the Maxwell equations emerge as the Euler-Lagrange equations that make the action stationary.
