“The most important fact is not that there are one or three or four or six identifiable periods of crisis in a lifetime; rather, adulthood unfolds its promise in an alternating rhythm of expansion and contraction, change and stability. In human life as in the rest of nature, change accumulates slowly and almost invisibly until it is made manifest in the sudden form of fledging out or thawing or leaf-fall. It is the transition process rather than a thing called “a mid-life transition” that we must understand.”