get the_content()

I want to make some modifications to all posts automatically.

In single.php, I can replace the_content() with

$post = get_the_content();
$post = manipulate($post);
echo "<p>".nl2br($post)."</p>";

But I see that the_content() replaces newlines with <p> tags.
Is there anyway I can somehow do

$post = the_content();
$post = manipulate($post);
the_content();

?

Thanks