How does Nadine Gordimer use imagery in The Conservationist?

Example of Imagery:

"He rolls onto his side, where he has the impression the reeds facing him hide him as drawn curtains keep out day. The sense of familiarity, of some kind of unwelcome knowledge or knowing, is slow to ebb. As it does, it leaves space in his mind; or uncovers, like the retreat of a high tide, carrying away silt."