public function log($message, $severity = null)
    {
        if (is_null($this->logger)) {
            $this->logger = LogManager::getLogger('propel');
        }

        switch ($severity) {
            case 'crit':
                $method = 'fatal';
                break;
            case 'err':
                $method = 'error';
                break;
            case 'alert':
            case 'warning':
                $method = 'warning';
                break;
            case 'notice':
            case 'info':
                $method = 'info';
                break;
            case 'debug':
            default:
                $method = 'debug';
        }

        // get a backtrace to pass class, function, file, & line to Mojavi logger
        $trace = debug_backtrace();

        // call the appropriate Mojavi logger method
        $this->logger->{$method} (
            $message,
            $trace[2]['class'],
            $trace[2]['function'],
            $trace[1]['file'],
            $trace[1]['line']
            );
    }