Need help with Pear Auth

[barnfargle]

The manual on pear.php.net gives the following example for using pear auth.

[code]

<?php
require_once "Auth.php";

function loginFunction()
{
    /*
     * Change the HTML output so that it fits to your
     * application.
     */
    echo "<form method=\"post\" action=\"test.php\">";
    echo "<input type=\"text\" name=\"username\">";
    echo "<input type=\"password\" name=\"password\">";
    echo "<input type=\"submit\">";
    echo "</form>";
}

$dsn = "mysql://user:password@localhost/database";
$a = new Auth("DB", $dsn, "loginFunction");

$a->start();

if ($a->checkAuth()) {
    /*
     * The output of your site goes here.
     */
}
?>

[/code]

How could I refer back to this page without having to show the login form again if the user has already authenticated, or span the authentication over multiple php pages?