What does the author's use of monochrome (black and white images) represent in the novel, Abigail?

In the novel, the narrator uses monochrome to symbolize austerity, discipline, and self-sacrifice, in contrast to the colorful, frivolous world represented by Gina’s old life in Budapest. The narrator frequently refers to the world of the Matula as “black and white” (18), with its starkly delineated parameters of right and wrong. The black and white quality of the school extends from its austere physical appearance — no colorful patterns are permitted — to its moral and spiritual pedagogy, which emphasizes strict adherence to the Bible and the renunciation of worldly adornments.