The speech 'Our revels now are ended' is famous as Shakespeare's farewell address to us, his audience. It is usually delivered indirectly to the theater audience by the retiring magician Prospero near the end of The Tempest , the last play written entirely by Shakespeare and written at the end of his career. The retiring magician of the theater has a retiring magician speak for him on stage. Though only 11 lines, that speech has a theme aside from how it fits into the play. Does it not behoove us to understand the parting message from the greatest writer, certainly in the English language, and maybe in the history of literature?
Our revels now are ended. These our actors,
As I foretold you, were all spirits and
Are melted into air, into thin air:
And, like the baseless fabric of this vision,
The cloud-capp'd towers, the gorgeous palaces,
The solemn temples, the great globe itself,
Yea, all which it inherit, shall dissolve
And, like this insubstantial pageant faded,
Leave not a rack behind. We are such stuff
As dreams are made on, and our little life
Is rounded with a sleep. -- The Tempest, Act 4 Scene 1
Of all the possible themes for a valedictory speech, Shakespeare chose this one. Perhaps the best analogy for the speech is a Buddhist sermon. An emphasis on the evanescence of all things is one of the distinguishing characteristics of Buddhism. "Impermanence" is the first of the Buddha's "Three Marks of Existence."
Shakespeare's art form allowed him to deliver his message more indelibly than even poetry, because this is also a demonstration. The language is plain, simple, and direct so that it won't distract from what Prospero is doing. The world of the play has "melted into air," was made of "baseless fabric," and was an "insubstantial pageant." He can emphasize each of these characterizations by gesturing toward the void on the stage created by the absence of the actors. The stage void stands in for the ultimate void. Likewise all of creation, even the listed most substantial examples, will some day "dissolve." A "rack" is a wisp of cloud.
The speech is delivered as an aside after a play-within-the-play. Prospero breaks away from a fit of anger to address the speech to his new son-in-law. At its end, Prospero breaks away from the speech when he suddenly feels faint. That the speech is an aside isolates and emphasizes it, which suggests the importance of its theme to Shakespeare.
He is not necessarily saying there is no God or afterlife or that life isn't worth living because of the devouring void. He's simply saying that someday, eventually, any material thing that you can imagine will be just as it was before it came into existence. Everything that has a beginning has an end. It is a truth profound, obvious, and irrelevant to any practical human concern. It is also, today, potentially scientifically provable. Some physicists suggest the universe must inevitably disappear due to proton decay.
Ecclesiastes has poetry about the ephemerality of creation. "One generation passeth away, and another generation cometh: but the earth abideth forever," (except Shakespeare says it too "shall dissolve"). Walt Whitman's poem "Sparkles from the Wheel" is a modernist take on the theme of the Shakespeare speech.
In the 1960s, the speech was featured in a cartoon by the great satirical cartoonist Lou Myers. He had a cockroach recite it. That's all. No explanation. However, there was a rumor back then, possibly an urban legend, that the cockroach is the only creature capable of surviving a nuclear Armageddon, the ultimate melting-into-thin-air.