A famous, yet simple, Taoist parable on the nature of reality, concerning the the philosopher Chuang Tzu, who was known, perhaps because of it, as "the butterfly philosopher":
One morning Chuang Tzu awoke from his sleep. Coming before his students, he said, "Last night I dreamt that I was a beautiful butterfly fluttering through the fields. Now I awaken. My question is this; how do I know if I am Chuang Tzu, who dreamt himself a butterfly, or if I am a butterfly, now dreaming itself Chuang Tzu?"
This story was the subject of a famous poem by Li Po. The basic issue raised by it is still relevant two-thousand-and-change years after the death of Chuang Tzu, perhaps now more than ever. How can we ever apprehend reality through our senses? When we spend a third of our lives dreaming, and now, many of our waking hours enveloped in what are essentially artfully manufactured waking dreams, how meaningful is our conception of an objective reality?
Whatever answer we come to, it's somehow comforting, to me at least, to think that better thinkers than me have been perplexed by the same problems for thousands of years.