An "energy method" to consider inequalities is described and the arithmetic-harmonic mean inequalitiey is interpreted in terms of electrical networks. A series-parallel network which yields a special case of Minkowski's reversed inequality can be found in this paper. The algebraic properties of the operatin parallel addition are described both in the scalar case and in the matrix case. A generalisation of Lehman's inequality into the matrix case can be found here too. Many applications, a brief discussion of the literature and some fairly new proofs and ideas are included.