Love and Water

The Comedy of Error's concluding dialogue between Dromio of Ephesus and Dromio of Syracuse neatly ties up an underlying theme of this farce, that true love — brotherly, marital or other — renders the lovers indistinguishable, “Methinks you are my glass, and not my brother.” But this metaphor of the mirror at the end of the play is a shift from the similes of drops of water that recurred previously. That concept was expressed by Antipholus of Syracuse in Act 1, Scene 2,

I to the world am like a drop of water,
That in the ocean seeks another drop…

and by Adriana in Act 2, Scene 3,

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.

Both use the simile of drops of water blended together, inseparable and indistinguishable. The theme is also alluded to by Antipholus of Syracuse's Act 3, Scene 2, in a different sense:

It is thyself, mine own self's better part:
Mine eye's clear eye, my dear heart's dearer heart,

The lovers blend and become in a sense one another, inseparable. But Dromio of Ephesus, at the end of the play while acknowledging the close bond of love between twins, also acknowledges some separation in the metaphor of a mirror. And he concludes the play with the couple:

We came into the world like brother and brother;
And now let's go hand in hand, not one before another.

The ending of Shakespeare's much later comedy/romance Cymbeline is evocative of the final scene of The Comedy of Errors. In Cymbeline the flags of England and Rome enter the Temple of Jupiter side by side, not as victor over vanquished, and Cymbeline says:

“…Let
A Roman and a British ensign wave
Friendly together.