The design of this Memoir is to deduce strictly from a few principles, obtained chiefly by experiment, the rationale of those electrical phenomena which are produced by the mutual contact of two or more bodies, and which have been termed galvanic; its aim is attained if by means of it the variety of facts be presented as unity to the mind.

Introductory sentence of Georg Simon Ohm (1891). The Galvanic Circuit Investigated Mathematically, translated by William Francis. D. Van Nostrand Co. p. 11.