public function addMessage( $message, $instance = null )
	{
		$sql = <<<SQL
INSERT INTO
	i18n_messages
SET
	message 	= ?,
	instance	= ?
SQL;

		return $this->Execute( $sql, array(
		                                  'tag' => 'Add message',
		                                  $message,
		                                  $instance
		                             ) );
	}