In his 1905 paper, Einstein says that when the magnet is in motion and conductor stationary, changing magnetic field in space develops electric field "of certain definite energy", and this starts current in the conductor. But in the reverse situation no electric field is produced in space but an electromotive force is produced in the conductor "to which there is no corresponding energy". What are these energies that he is referring to? Why there is no energy in the reverse case? Why asymmetry is troublesome? And how it indicates that Maxwell's laws are frame independent?