  Due to the fact that only matter fields have phase, frequently is believed
that the gauge principle can induce gauge fields only in quantum systems. But
this is not necessary. This paper, of pedagogical scope, presents a classical
system constituted by a particle in a classical potential, which is used as a
model to illustrate the gauge principle and the spontaneous symmetry breaking.
Those concepts appear in the study of second order phase transitions.
Ferroelectricity, ferromagnetism, superconductivity, plasmons in a free
electron gas, and the mass of vector bosons in the gauge field Yang-Mills
theories, are some of the phenomena in which these transitions occur.
