Closures and scope

[nop]

Snippet from perlref:

sub newprint {
        my $x = shift;
        return sub { my $y = shift; print "$x, $y!\n"; };
    }
    $h = newprint("Howdy");
    $g = newprint("Greetings");
    # Time passes...
    &$h("world");
    &$g("earthlings");

This prints

    Howdy, world!
    Greetings, earthlings!

Note particularly that $x continues to refer to the value passed into 
+newprint() despite ``my $x'' having gone out of scope by the time the
+ anonymous subroutine runs. That's what a closure is all about.

Can someone explain the last cryptic paragraph? It seems to me that "my $x" has gone out of scope by the time the anon sub runs... is the value still around because there remains a ref to it? If so, what is doing the ref... the anon sub itself? Clarification welcome... thanks.