  Motivated mainly by the fact that no charged elementary particles having zero
mass have been observed up to now, we investigate the question whether the mass
of the elementary particles is connected with their electric charge and whether
gravity can be derived from QED. The graviton is considered as a two-photon
bound state. A relation between mass and charge of elementary particles is
derived. Masses of the light quarks $d$ and $u$ are calculated from the
electron mass, assuming that $d$, $u$ and $e$ are all fundamental and not
composite. In this picture, the heavier quarks and leptons are considered as
not fundamental, the massive neutral gauge bosons (and then their charged
partners) are composite. The here calculated $u$ and $d$ quark masses, result
in quark-mass ratios which display interesting regularities. The lightest quark
mass turns out to be quite small. This may be interesting in connection to the
strong CP problem.
