I am that merry wanderer of the night.
I jest to Oberon and make him smile
When I a fat and bean-fed horse beguile,
Neighing in likeness of a filly foal. (II.i.)

In Act II, Puck says these words in response to an unnamed fairy who identifies Puck and celebrates his infamous mischief. Here Puck describes the role he plays for Oberon, which is not unlike that of a jester, albeit a magical one. In the particular example he gives here, Puck amuses Oberon by tricking a horse into thinking he’s a young mare.

I’ll follow you. I’ll lead you about a round,
Through a bog, through bush, through brake, through brier.
Sometime a horse I’ll be, sometime a hound,
A hog, a headless bear, sometime a fire,
And neigh, and bark, and grunt, and roar, and burn,
Like horse, hound, hog, bear, fire, at every turn. (III.i.)

Puck utters these lines as an aside in Act III, after he’s transformed Bottom’s head into that of a donkey and the rest of the craftsmen have run away. Puck indicates he’ll lead the craftsmen in circles (i.e., “about a round,” meaning in a circular dance) through the forest, and that he’ll continue to frighten them by assuming various animal and inanimate forms. Puck’s sing-song wordplay in these lines serves to express his delight in creating mischief.

Then fate o’errules, that, one man holding troth,
A million fail, confounding oath on oath. (III.ii.)

Puck says this line in Act III, responding to Oberon’s frustration that Puck applied the charm to the wrong person; he was meant to charm Demetrius, but charmed Lysander by mistake. With these words Puck implies that fault must not ultimately lie with him, but with fate. Puck declares that for each man who keeps his word, as he himself has done, a million others do not.

And those things do best please me
That befall prepost’rously. (III.ii.)

In Act III Puck utters these words to express his love of mischief. His use of the word “prepost’rously” is significant. The word derives from the Latin prepositions prae (in front of, before) and posterus (behind, after). Thus the word literally means “back first.” In the Renaissance period “preposterous” was used to describe inversions of the normal order of things, and especially of social and sexual norms. It therefore suggested monstrosity and perversity. Puck clearly enjoys the perversity of such inversions.

Up and down, up and down,
I will lead them up and down.
I am feared in field and town.
Goblin, lead them up and down. (III.ii.)

Puck sings this song in Act III as he sets off to lead the lovers in circles, eventually tiring them out and bringing them together so he can re-charm the men and set things right. The phrase “up and down” functions nicely as a metaphor for the mischief Puck has already caused. These words may also be an allusion to John Farmer’s 1599 madrigal “Fair Phyllis,” where the refrain “up and down” features prominently as a humorous code for sex. The allusion is appropriate, since Puck’s goal at this moment is to unite two pairs of lovers.

Jack shall have Jill.
Nought shall go ill. (III.ii.)

The simplicity and straightforwardness of this rhyming couplet indicates that, after so much confusion, Puck truly intends to reverse his mischief and set things right again. Given the legal problems the lovers left behind in Athens, Puck’s words also unwittingly imply that once each “Jack” has been united with his proper “Jill,” nothing further will stand in their way once they return to the city.

If we shadows have offended,
Think but this, and all is mended:
That you have but slumbered here
While these visions did appear.
And this weak and idle theme,
No more yielding but a dream,
Gentles, do not reprehend. (V.i.)

These are Puck’s parting words to the audience at the end of Act V. Here the word “shadows” refers to the actors in the play that now comes to a close. Puck’s words echo a speech Oberon gave earlier in the play, when he said the lovers, upon waking, would consider their night in the forest but a harmless dream. Puck encourages us to think the same about the play. No one should leave feeling disturbed by what they’ve seen. In this sense, Puck’s closing words also echo the concerns the craftsmen had about not offending their audience, lest they face dire consequences.