Prologue:Henry The Eighth Prologue, 23–25
Therefore, for goodness sake, and as you are known
The first and happiest hearers of the town,
Be sad, as we would make ye.
Wolsey:Henry The Eighth Act 3, scene 1, 159–161
For goodness sake, consider what you do,
How you may hurt yourself—ay, utterly
Grow from the King's acquaintance, by this carriage.
It's unusual that the first time a phrase appears in surviving literature it appears twice in the same place. The repetition suggests that the author was used to the phrase, which was perhaps becoming common when Henry the Eighth was composed—around 1613, Since the play is apparently a collaboration between Shakespeare and his successor John Fletcher, it's hard to be certain whose words "for goodness sake" are—the prologue, in any case, doesn't sound Shakespearean.
"For goodness' sake"—an Elizabethan wouldn't use the apostrophe as we're required to—has its literal force here: "for the sake of goodness and decency." The prologue petitions the play's first "hearers" (audience) to be "sad" (serious) for the sake of one kind of goodness—politeness or kindness. Cardinal Wolsey—a real snake in the grass—urges Queen Katherine to mend her petulant "carriage" (behavior) for the sake of a more general goodness—goodness in the abstract. As the phrase became more and more common, it lost its status as an adverb and became a simple interjection—just like its counterpart, "For God's sake." We usually use it to verbally throw up our hands rather than to urge any particular action for the sake of goodness.
Themes: expressions and idioms