PHP类与对象中的private访问控制的疑问

复制代码 代码如下:
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

为啥第一行会输出Bar::testPrivate呢？
一些资料： 
https://www.jb51.net/article/31709.htm
还有php官网上，关于这段代码的贡献者回复中，也找到了一条：
http://www.php.net/manual/zh/language.oop5.visibility.php#87413