  Let $lu = -u^{\prime \prime} + q(x)u$, where $q(x)$ is a real-valued
$L^2_{loc}(0, \infty)$ function. H. Weyl has proved in 1910 that for any $z$,
$Imz \neq 0$, the equation $(l - z)w=0$, $x>0$, has a solution $w \in L^2(0,
\infty)$.
  We prove this classical result using a new argument.
