PHP手动OOP可见性示例-有人能解释一下吗

我在PHP OOP手册中看到了这一点http://www.php.net/manual/en/language.oop5.visibility.php我无法理解为什么输出不是：Foo:：testPrivate Foo:：testPublic

class Bar 
{
    public function test() {
        $this->testPrivate();
        $this->testPublic();
    }
    public function testPublic() {
        echo "Bar::testPublic'n";
    }
    private function testPrivate() {
        echo "Bar::testPrivate'n";
    }
}
class Foo extends Bar 
{
    public function testPublic() {
        echo "Foo::testPublic'n";
    }
    private function testPrivate() {
        echo "Foo::testPrivate'n";
    }
}
$myFoo = new foo();
$myFoo->test(); // Bar::testPrivate 
                // Foo::testPublic