Getting the auto summary from a node body I load an Article node with node_load() and I'd like to get the summary for the Body field. I know that I can access it with $node-&gt;body[$node-&gt;language][0]['summary'] but unless the user explicitly adds a Summary Body, then this field is empty. 

I know that drupal will automatically generate a "trimmed body" if they don't add a Summary Body. How can I access that trimmed body?

EDIT:

I'm not interesting in render()ing the content, I just want the text. My module is generating a json feed for an external source.
node_view() is appropriate when you need to render whole node or many of it's fields.
But sometimes you have to render the only field you need. It can be done with field_view_field() or field_view_value():
$node = node_load($nid);
// Render array of body field.
$build_body = field_view_field('node', $node, 'body', 'teaser');
// Render it in common way.
echo render($build_body);

The interesting thing is that you can pass your own field formatter settings instead of view mode with the fourth parameter.
Please, read API docs for more info.