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Newton published his theory of gravitation in his monograph Philosophiae Naturalis Principia Mathematica. Newton viewed the gravitational interaction between two masses through force. The effect of static electricity was known for a long time, at least since 600 BC. However, only in 1600, Gilbert carried out systematic studies of both magnetism and static electricity. The static electricity was generated by the rubbing of two specific objects. He suggested the word electricus for electricity, and the English word “electricity” was suggested by Thomas Browne in 1646. Gilbert also suggested that the electrical effect is due to the flow of a small stream of weightless particles called effluvium. This concept helped the formulation of one‐ and two‐fluid model of electricity. He also invented the first electrical measuring instrument, the electroscope, which helped further experimental investigations on electricity.

In 1733, Fay proposed that electricity comes in two forms – vitreous and resinous, and on combination, they cancel each other. The flow of the two forms of electricity was explained by the two‐fluid model. During this time interval, around up to 1745, the electrical attraction and repulsion were explained using the flow of Gilbert's particle effluvium. In 1750, Benjamin Franklin proposed the one‐fluid model of electricity. The matter containing a very small quantity of electric fluid was treated as negatively charged, and the matter with excess electric fluid was treated positively charged. Thus, the negative charge was resinous electricity, and the positive charge was vitreous electricity. Now, the stage was ready for further theoretical and experimental investigations on electricity.

In the year 1773, Lagrange introduced the concept of the gravitational field, now called the scalar potential field, created by a mass. The gravitational force of Newton was conceived as working through the gravitational field. The scalar potential field has appeared as a mechanism to explain the gravitational force interaction between two masses. Thus, a mass located in the potential field, described by a function called the potential function, experiences the gravitational force. In 1777, Lagrange also introduced the divergence theorem for the gravitational field. The nomenclature potential field was introduced by Green in 1828. Subsequently, Gauss in 1840 called it “potential.” Laplace in 1782 showed that the potential function ϕ (x,y,z) satisfies the equation ∇²ϕ = 0. Now the equation is called Laplace's equation.

Following the Law of Gravitation, Coulomb postulated similar inverse square law, now called Coulomb's law, for the electrically charged bodies. He experimentally demonstrated the inverse square law for the charged bodies in 1785. Thus, the mathematical foundation of the EM‐theory was laid by Coulomb. The law was also applicable to magnetic objects. The interaction between charged bodies was described by the electric force. In the year 1812, Poisson extended the concept of potential function from the gravitation to electrostatics. Incorporating the charge distribution function ρ, he obtained the modified Laplace's equation, written in modern terminology, ∇²ϕ = −ρ/ε₀. This equation now called Poisson's equation is the key equation to describe the potential field due to the charge distribution. In the same year, Gauss rediscovered the divergence theorem originally discovered by Lagrange for the gravitational field.

In the year 1828, Green coined the nomenclature – the potential function, for the function of Lagrange and modern concept of the scalar potential field came into existence. Green also showed an important relation between the surface and volume integrals, now known as Green's Theorem. Green applied his method to the static magnetic field also. Green also introduced a method to solve the 3D inhomogeneous Poisson partial differential equation where the considered source is a point charge. The point charge is described by the Dirac's delta function. The solution of the Poisson's partial differential equation, using Dirac's delta function, is now called Green's function. Neumann (1832–1925) extended the Green's function method to solve the 2D potential problem and obtained the eigenfunction expansion of 2D Green's function [J.1–J.5, B.2, B.7].