How does Charles Dickens use imagery in Oliver Twist?

Imagery:

He looked like death; not death as it shows in shroud and coffin, but in the guise it wears when life has just departed; when a young and gentle spirit has, but an instant, fled to Heaven, and the gross air of the world has not had time to breathe upon the changing dust it hallowed.

The boy stirred, and smiled in his sleep, as though these marks of pity and compassion had awakened some pleasant dream of a love and affection he had never known. Thus, a strain of gentle music, or the rippling of water in a silent place, or the odour of a flower, or the mention of a familiar word, will sometimes call up sudden dim remembrances of scenes that never were, in this life; which vanish like a breath; which some brief memory of a happier existence, long gone by, would seem to have awakened; which no voluntary exertion of the mind can ever recall.