As a result of all this the theory of electricity has fallen apart into several conceptual realms lying, as it were, alongside one another, each consistent in itself but lacking any logical connexion with the others. Although the old concept of the electric current has long lost its validity, scientific thought (not to speak of the layman's) has not managed to discard it. To do this must therefore be our first task, if we want to attain to a realistic picture of electromagnetism.