public function getBaseDirectory($directoryToAppend = null)
    {

        // load the base directory from the system configuration
        $baseDirectory = $this->getSystemConfiguration()->getBaseDirectory();

        // if a directory has been passed, make it absolute and append it
        if ($directoryToAppend != null) {
            $baseDirectory .= $this->makePathAbsolute($directoryToAppend);
        }

        // return the base directory, with the passed path appended
        return $baseDirectory;
    }