He is implying that because of their basic living conditions, they were not being given a fair amount of opportunity that the American Dream clearly promises.
These two settings are juxtaposed as the brush is free, open and beautiful whereas the bunkhouse is confined, claustrophobic and plain. The brush is described as a place where you can see the water ‘twinkling over the yellow sands’ and where the leaves are ‘crisp’. The ‘horizontal limb of a giant sycamore’ tells us that the brush is a large place if it can hold something with of a big size, showing the natural beauty. On the other hand, the bunkhouse is ‘whitewashed’ and ‘unpainted’ showing the plain walls and also the ‘small, square windows’ emphasise the cramped place they must live in. Steinbeck uses the contrast between these two settings to show the large contrast between the reality and the perfect world. The American Dream tells people that they can ‘attain to the fullest stature’ and yet Steinbeck tells them in this novel that they cannot.
In conclusion, I think that throughout the novel, settings are used well to show Steinbeck aims of proving the American Dream to be false hope as the ‘fifty bucks’ they get each week gives them very little. Their basic living conditions of ‘two shelves’ in this ‘whitewashed’, ‘rectangular’ building tells us that they are not given enough opportunity to improve themselves as their pay is not enough to accommodate