The Author iliistrated the theme by using character thoughts for example:
When mary came back home, she thought " Do everything right and natural. Keep things absolutely natural and there'll be no need for any acting at all."
."She put the parcel down on the table and went through into the living room"; and when she saw him lying there on the floor with his legs doubled up and one arm twisted back underneath his body, it really was rather a shock.
I don't know if this can help :)
