The opening lines of Shakespeare's Twelfth Night read:

If music be the food of love, play on;
Give me excess of it, that, surfeiting,
The appetite may sicken, and so die.
That strain again! it had a dying fall:
O, it came o'er my ear like the sweet sound,
That breathes upon a bank of violets,
Stealing and giving odour!

Alexander Pope emended the word sound (line 5) to south.

A discussion of Pope's motive for this emendation is discussed here: