  In this paper we give the outline of a lecture given to undergraduate
students aiming at understanding why physicists are so much interested in the
Higgs boson. The lecture has been conceived for students not yet familiar with
advanced physics and is suitable for several disciplines, other than physics.
The Higgs mechanism is introduced by semi-classical arguments mimicking the
basic field theory concepts, assuming the validity of a symmetry principle in
the expression of the energy of particles in a classical field. The lecture is
divided in two parts: the first, suitable even to high--school students, shows
how the mass of a particle results as a dynamical effect due to the interaction
between a massless particle and a field (as in the Higgs mechanism). The
audience of the second part, much more technical, consists mainly of teachers
and university students of disciplines other than physics.
