title: Why is System.out.println(super) not permitted?
body: <p>Why is <code>System.out.println(super)</code> not permitted?</p>
  
  <pre><code>System.out.println(this);
  </code></pre>
  
  <p>This is OK and <code>this.toString()</code> is called and printed automatically.
  Of course, instance variable is OK instead of <code>this</code>.</p>
  
  <p>However, <code>this</code> and <code>super</code> can be used in same way as I know.</p>
  
  <pre><code>System.out.println(super);
  </code></pre>
  
  <p>So why does this fail? I think it's supposed to call <code>super.toString()</code> implicitly.
  I have read Java specification document, but I haven't found the reason.</p>