How does Olga Lengyel use imagery in Five Chimneys: The Story of Auschwitz?

Imagery:

"Of all the horrible tasks I had to do, this one left me with the ghastliest memories. I refuse to elaborate further to describe how we had to trample over the accumulations of rotting, putrid cadavers, many of whom had died from frightful diseases." Chap. XII, p. 97

"New Year's Eve ... Somewhere on earth, beyond the barbed wires, free men were shaking hands and raising their glasses to wish each other Happy New Year! At Birkenau rats were feeding on the children of Europe." Chap. XXVII, p. 224