We not only live longer, we change our spouses, our jobs, our vocations, our homes much more often. Whole sections of our lives, like the time between fifty and seventy and the time between seventy and ninety are filled with new experiences. Maturation is stretched out, so that even life-chunks that most of us lived through a century ago — like the years from thirteen to twenty-three — are much richer in variety and in the modulations of growing up. So the simpler markers of a simpler life no longer satisfy.

Arthur Waskow, Phyllis Ocean Berman, A Time For Every Purpose Under Heaven