  We enlarge the local gauge invariance of QED from $~U(1)_A~$ to $~U(1)_A
\times U(1)_{\Theta}~$ by introducing another unphysical pure gauge field
$~\Theta~$ with an independent, unphysical gauge coupling $~\tilde{e}~$. This
pure gauge field can be gauge-transformed away and the resulting theory is {\it
identical to} standard QED. We then re-examine the Dirac quantization condition
(DQC) for point monopoles and find that two essentially different DQCs can be
derived. One DQC involves a gauge coupling $~e~$ in the $~U(1)_A~$ group and
the other only the unphysical gauge coupling $~\tilde{e}~$ in the
$~U(1)_{\Theta}~$ group. The unique physically consistent solution of these two
DQCs is a vanishing magnetic charge, which implies that no Dirac monopole
exists in nature.
