Describe symbolism in A Bend in the River by V. S. Naipaul

The first sentence of the book is a bleak judgment, "The world is what it is; men who are nothing, who allow themselves to become nothing, have no place in it." Salim questions what kind of person could be considered a nothing and what he or she may have done to deserve being considered as such. It's clear that he doesn't think Zabeth is nothing. For him, she symbolizes authentic Africa, and he admires how fearlessly she travels the river and comes in and out of the bush. Perhaps, the key to the sentence is not nothingness, but people who allow themselves to be nothing.