The first equations are originally from Gauss. They describe the net magnetic field and electric field produced from inside an enclosed surface. A charge inside a closed surface produces a net flux and an electric field. A magnet enclosed inside a closed surface, however, does not produce a net magnetic flux because magnetic mono-poles are thus far unknown to science and may not exist. The third equation is Faraday's Law and the fourth is Ampere's Law. Together they make Maxwell's Equations. He was like the editor. The third equation, Faraday's Law, essentially states that an electric field is produced by a changing magnetic field. And the fourth equation states that a magnetic field is produced by an electric current OR a changing electric field.