It's the classic mistaken-identity sitcom episode, more or less. Two brothers, separated as children, both named Antipholus (I just missed the other kid so much, I named the one I kept Antipholus too, says the bereaved father) end up in Ephesus, where one lives. In case that's not absurd enough for you, they each have a manservant named Dromio. When Antipholus of Syracuse comes to Ephesus, well... you can probably imagine what kind of hijinks ensue.
Comedy of Errors is true to its name, delivering up a series of pretty funny set pieces that involve the Antipholuses and Dromios confusing one another. The best moment, I think, comes when Dromio of Syracuse encounters the wife of Dromio of Ephesus, whom he describes this way:
DROMIO OF SYRACUSE: ...She is spherical, like a globe. I could find out countries in her.
ANTIPHOLUS OF SYRACUSE: In what part of her body stands Ireland?
DROMIO: Marry, sir, in her buttocks. I found it out by the bogs.
ANTIPHOLUS: Where Scotland?
DROMIO: I found it by the barrenness, hard in the palm of her hand.
ANTIPHOLUS: Where France?
DROMIO: In her forehead, armed and reverted, making war against her heir.
ANTIPHOLUS: Where England?
DROMIO: I looked for the chalky cliffs, but I could find no whiteness in them. But I guess it stood in her chin, by the salt rheum that ran between France and it.
ANTIPHOLUS: Where Spain?
DROMIO: Faith, I saw it not, but I felt it hot in her breath.
ANTIPHOLUS: Where America, the Indies?
DROMIO: O, sir, upon her nose, all o'er embellished with rubies, carbuncles, sapphires, declining their rich aspect to the hot breath of Spain, who sent whole armadas of carracks to be ballast at her nose.
ANTIPHOLUS: Where stood Belgia, the Netherlands?
DROMIO: O, sir, I did not look so low.
If ever Shakespeare needed a rimshot, it's here. If there is any real depth to the play, it comes from the theme of losing one's identity, which is what worries the Syracusan Antipholus:
He that commends me to mine own content
Commends me to the thing thing I cannot get.
I to the world am like a drop of water
That in the ocean seeks another drop,
Who, falling forth there to find his fellow forth,
Unseen, inquisitive, confounds himself.
Antipholus sets up a paradox in which he searches for his brother to individuate himself, to become again a whole drop of water, even though to do so he must confront his own sameness by finding him. The water-drop motif is repeated unintentionally by Adriana, the wife of Ephesian Antipholus, whose worry about her husband's disinterest is only exacerbated by the fact that he no longer seems to recognize her:
Ah, do not tear thyself away from me;The bittersweetness of these lines is not like anything else in the play, and stands out in sharp relief. By contrast the Ephesian Antipholus, in whom the identities of his wife and brother are so intimately tangled, walks through the play caddishly unconcerned with anyone else. Perhaps, if you want to look past the slapstick, the message here is that real human relationships imply the risk of losing one's own identity--but the alternative is just being a selfish jackass.
For know, my love, as easy mayst thou fall
A drop of water in the breaking gulf,
And take unmingled thence that drop again
Without addition or diminishing,
As take from me thyself, and not me too.