The "Ianthe" of the dedication was the term of endearment he used for Lady Charlotte Harley.
One of her earliest roles was in The Siege of Rhodes, taking over the role of Ianthe in place of a Mrs. Edward Coleman, whom many agreed had done very poorly in the role.
The 17th-century publisher Humphrey Moseley once claimed to possess a manuscript of a play based on the Iphis and Ianthe story, by William Shakespeare.