How does Erik Larson use imagery in In the Garden of Beasts: Love, Terror, and an American Family in Hitler's Berlin?

Imagery:

"From the neck down to his heels he was a mass of raw flesh."

"Berlin is a skeleton which aches in the cold. . .It is my own skeleton aching. I feel in my bones the sharp ache of the frost in the girders of the overhead railway, in the ironwork of balconies, in bridges, tramlines, lamp-standards, latrines. The iron throbs and shrinks, the stone and the bricks ache dully, the plaster is numb."