James Clerk Maxwell Quote
What, then, is light according to the electromagnetic theory? It consists of alternate and opposite rapidly recurring transverse magnetic disturbances, accompanied with electric displacements, the direction of the electric displacement being at the right angles to the magnetic disturbance, and both at right angles to the direction of the ray.
The Scientific Letters and Papers of James Clerk Maxwell: (ed. CUP Archive, 1995) - ISBN: 9780521256261