A Dynamical Theory of the Electromagnetic Field
"A Dynamical Theory of the Electromagnetic Field" is a paper by James Clerk Maxwell on electromagnetism, published in 1865. Physicist Freeman Dyson called the publishing of the paper the "most important event of the nineteenth century in the history of the physical sciences".
The paper was key in establishing the classical theory of electromagnetism. Maxwell derives an electromagnetic wave equation with a velocity for light in close agreement with measurements made by experiment, and also deduces that light is an electromagnetic wave.