As a black time traveller, the character of Martha allows "Doctor Who" to explore historical issues concerning race. In the episode "The Shakespeare Code", Martha wonders if she is safe in an era before emancipation, but the Doctor is unconcerned. The Doctor points out to Martha (also the audience surrogate) that England in 1599 is "not so different from your time"; black women are seen walking amongst the crowd at home and safe, and Martha identifies several cross-dressing actors. Martha soon reacts with surprise and possible offence to William Shakespeare's use of Elizabethan terms for black people such as "" and "ethiop". For a moment, she thinks these terms could be racist (the Doctor quips that it is "political correctness gone mad"), but realises Shakespeare is actually enamoured of her. At the end of the episode, he calls her his "Dark Lady", the name given to the woman the real Shakespeare referred to in a number of Shakespeare's sonnets; by implication, Martha is the Dark Lady. Lindy A. Orthia opines that such Tenth Doctor era representations of "Earth’s past as a place of happy and benign diversity" may be anti-racist in intention, but ultimately trivialise the racism that she claims has "infested" Western society for centuries. Such representations include visions of "Depression-era New York mixed-race shanty towns led by a black man ("Daleks in Manhattan"), while black women populate the streets and royal courts of Victorian England and Enlightenment France".