"what if she were simply to open her bedroom window and throw herself out, head first? Would she really be able to come back and start again? Or was it, as everyone told her, and as she must believe, all in her head? And so what if it was--wasn't everything in her head real too? What if there was no demonstrable reality? What if there was nothing beyond the mind? Philosophers "came to grips" with this problem a long time ago, Dr. Kellet had told her, rather wearily, it was one of the very first questions they addressed, so there was really no point in her fretting over it. But surely, by its very nature, everyone wrestled with this dilemma anew every time?"