Although you generally want to avoid using too many short quotes when you write, there are times when you need to quote a word or a phrase as a part of your own sentence. Short phrases and single words should work smoothly with the structure of your own sentence. Look, for example, at the way the brief passages from Thoreau’s Walden flow into the surrounding sentence:
The demands of a market economy, in fact, would penalize a man who chose to give precedence to relationships and “true integrity” over labor: an over-emphasis on work leaves a man dehumanized and with “no time to be anything but a machine” (Thoreau 21).