A sea change

The phrase originated in Shakespeare’s play The Tempest, 1610:

ARIEL [sings]:
Full fathom five thy father lies;
Of his bones are coral made;
Those are pearls that were his eyes:
Nothing of him that doth fade
But doth suffer a sea-change
Into something rich and strange.
Sea-nymphs hourly ring his knell

Shakespeare’s usage incorporates the current meaning, that is, a radical change. He also made the expression richer by alluding to the literal meaning of ‘a change that is brought about by the sea’.