With the advent of Quantum Chromodynamics (QCD) which is believed to be the underlying theory of strong interactions, one is entitled to demand that hadron physics be described in terms of the degrees of freedom of the fundamental constituents in QCD. The trouble is that QCD has a running coupling constant \01(q2). For large momentum transfers q, as in the region of deep inelastic scattering of leptons by hadrons, \01(q2) is small. One can use there perturbation theory to make theoretical predictions which turn out to be in good agreement with experiment.