Question

Where did this quote come from "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
If you pardon, we will mend

Answer 1

A Midsummer Nights Dream, Shakespeare, act 5 Scene 1

Monologue by Puck.

Answer 2

 Shakespeare's A Midsummer Night’s Dream