A Midsummer Night's Dream is a comedy written by William Shakespeare c. 1595 or 1596. The play is set in Athens, and consists of several subplots that revolve around the marriage of Theseus and Hippolyta. One subplot involves a conflict among four Athenian lovers. Another follows a group of six amateur actors rehearsing the play which they are to perform before the wedding. Both groups find themselves in a forest inhabited by fairies who manipulate the humans and are engaged in their own domestic intrigue. The play is one of Shakespeare's most popular and is widely performed. While one dreams, one does not normally realize one is dreaming. On more rare occasions, the dream may be contained inside another dream with the very act of realizing that one is dreaming, itself, being only a dream that one is not aware of having. This has led philosophers to wonder whether it is possible for one ever to be certain, at any given point in time, that one is not in fact dreaming, or whether indeed it could be possible for one to remain in a perpetual dream state and never experience the reality of wakefulness at all.