  We determine the epimorphisms $A \to W$ from the Artin group $A$ of type
$\Gamma$ onto the Coxeter group $W$ of type $\Gamma$, in case $\Gamma$ is an
irreducible Coxeter graph of spherical type, and we prove that the kernel of
the standard epimorphism is a characteristic subgroup of $A$. This generalizes
an over 50 years old result of Artin.
