A black maid enters. Cowed, inarticulate, she makes obeisance to her mistress, our erstwhile heroine.
She is given a menial task in a perfunctory fashion, and you thrill at this splash of historical colour.
But her mistress's command is irrelevant. She is fully engaged with two vital functions with which I have entrusted her.
The first: she has bathed our heroes in moral ambiguity - she is a shortcut to complexity, rendering the important characters doubly fascinating, bathing them in pathos.
The second: she has pleased you as you recognise your own outrage: "Why must she be black? Why can't they treat her better? Don't we live in finer times, you and I?" And a happy reader is a reader who will proceed, enlivened, vindicated, affirmed.
And thus freshly enslaved, she returns to the sculleries of my imagination as we press nobly on.