To “cut to the chase”, Kairos is one of the concepts of time developed by the ancient Greeks, along with Chronos and Aion … Chronos being the “flowing” sequential time of daily experience, what the clock tracks, Aion being “eternal” time, or what appears to me to be the fourth axis of a 4-dimensional space, with Kairos being “the right time”, or “opportunity” (based on the Latin translation of Kairos). Kairos then dovetails with propriety and efficiency … the word itself appears to have come from ancient archery as being the moment when an arrow could pass through interspersing obstacles to find its target (I can't help to think of a football pass that splits tight double coverage to end up in the arms of the receiver). The concept is fairly common, but not so much in the terminology. The English translation of the Bible frequently places Kairos in terms of “a time to”, much like in Ecclesiastes 3:1 (or The Byrds' Turn! Turn! Turn!) “To every thing there is a season”.
However, rather than being a book about Kairos, what the editors have produced is a series of academic papers that deal with Kairos in a variety of contexts, largely assembled in a chronological order. As is often the case with collections of disparate materials like this, the tone and structure of each paper differs, making the reading experience uneven (not that one would pick up Rhetoric and Kairos for light “enjoyment” reading anyway). The first seven pieces here discuss the concept of Kairos, and how it functioned within the context of Ancient Greece, and in the writings of several famed philosophers. As one would expect from the title, much of the focus here is on the rhetorical applications in Athens and elsewhere.
The book then moves into looks at Kairos in the New Testament, in Roman writings, in the Renaissance, in Shakespeare's Hamlet, in the writings of Ralph Waldo Emerson, in the arts, in “composition classes”, and closes with a proposition for an “ethics of Kairos”.
Being that I got this via a clearance sale, I was surprised to find that it is still available via the on-line guys, which leads me to think that this is likely a college text book. It is also listed with them without any discount and there are no “cheap” copies in the used channels (although there are some there at less than half of cover). Of course, I doubt anybody reading this is aching to pick up a copy (it is both academic and a bit obscure), but if it sounds like something you'd find of interest, it is at least something you can order.