Since I've first heard about electricity and magnetism, people always said me that the electric and the magnetic field are nothing less than two sides of the same coin. I really wasn't convinced of that. I've entered at college. Nothing. And I took a (pitiful) undergraduate course on Electromagnetism. Nothing. Not even the Maxwell Equations and the explanation about how they demonstrate the existence of EM waves convinced me. It always appeared that The electric and the magnetic field were two separated things, no matter how much relations between them. I tried even graduate books (say, Jackson), and nothing.
Then, Here comes the light... Schwartz' chapter about electric field and relativity, where he concludes merely from Coulomb law and Lorentz invariance that MUST BE A MAGNETIC FIELD, then comes with the EM Field Strength tensor and derives (also from Lorentz invariance)... the very Maxwell's equations! Unbelievable! Why didn't they tell me this before? Or, why don't they teach EM like this? All this not to mention the section about an insight over determining nuclear shape from electric quadrupole moments, the tensorial form of EM laws, Multipole expansion, all that with a remarkable physical insight that is so rare in EM texts (maybe other exception is Landau's Classical Theory of Fields). I only regret the absence of a Lagrangian-Hamiltonian formulation for EM, Green's functions, and gauge invariance with his properties and how this reflect in the formulation of EM laws. But I believe that these topics can be well covered in Landau's text (I really hope so, so I don't need to rely on the insight-less text from Jackson). After all, the physical unity, simplicity and beauty of Schwartz's book is nearly unbeatable. 5 stars "cum lauda"!