Sentence:  To believe that such talk really ever came out of people's mouths would be to believe that there was a time when time was of no value to a person who thought he had something to say; when it was the custom to spread a two-minute remark out to ten; when a man's mouth was a rolling-mill, and busied itself all day long in turning four-foot pigs of thought into thirty-foot bars of conversational railroad iron by attenuation; when subjects were seldom faithfully stuck to, but the talk wandered all around and arrived nowhere; when conversations consisted mainly of <WSD>irrelevancies</WSD>, with here and there a relevancy, a relevancy with an embarrassed look, as not being able to explain how it got there. 
Meaning of the word marked with <WSD> tags:  A thing that is irrelevant—having no bearing on the subject of discussion.