This book is composed of a series of essays written by Dr. Percy over a period of twenty years from 1954 to 1975. All have been published in journals except the last one, "A Theory of Language." The first one was written before his first novel, The Moviegoer, was published. These all reflect his recurring interest in the nature of human communication.

The first essay, "The Delta Factor," is perhaps the easiest to understand. It has a long subtitle: "How I Discovered the Delta Factor Sitting at my Desk One Summer Day in Louisiana in the 1950's Thinking About an Event in the Life of Helen Keller on Another Summer Day in Alabama in 1887." Percy asks why man feels so sad in the twentieth century; he goes on to state that this book is about two things: man's strange behavior, and man's strange gift of language and how understanding the latter might help understanding of the former.

Percy's view is that man's singular asset, which differentiates him from animals, is language. His interest in language and how children acquire language is almost certainly related to the fact that one of his daughters is deaf, hence also his interest in Helen Keller. Subsequent essays are further approaches to these questions, including the importance of symbolization as an essential act of the mind and a basic human need.

The essay, "The Message in the Bottle" is built around the supposition that a man who is a castaway on an island and has no memory of his past life finds on the shore a series of bottles which contain messages. The man, who has become a useful member of the island community, must decide which messages appear to state empirical facts and which seem to refer to the nature of reality. Dr. Percy sees that the messages can be in some ways like the news of the Christian faith. This fits with his own personal way of dealing with a feeling of alienation by turning to religion. He sees belief in one of the theistic historical religions as a way to redeem man from the catastrophe which has overtaken him. He describes not only himself but also man as a castaway who can recognize his need and have hope that some message might relieve his predicament.