If you travel up to the Munson-Williams-Proctor Institute in Utica, New York, you can see the four enormous river and landscape paintings in Thomas Cole’s landmark 1842 series The Voyage of Life. Together, they depict the familiar metaphor of life as a journey through different stages: Childhood, represented by a plump infant; Youth, by an androgynous-looking teenager; Manhood, by a strapping, bearded figure; and Old Age, a seated, white-haired man of 70 or more. These four broad and vague categories, popularized in journals and schoolbooks in 18th and 19th century America, reflected the way that men and women then viewed themselves. The young have “vigor and firmness,” an orator told the crowd at the 1825 groundbreaking for an Ohio canal, manhood is endowed with “strength and firmness” and old age “confers wisdom.”The elderly’s insight and experience were all the more valuable given how few there were -- 4 percent of the population was over 65 – like a white Bengal tiger amidst a streak of orange-and-blacks. Middle age did not merit a mention. It had not been invented yet.
The absence may seem curious, but for early Americans the midsection of life did not seem worth discussing or formally labeling. “It appears, in fact, that they did not regard this interim period as distinctive at all,” the historian John Demos has written. “Instead, the middle years represented for them simply the full flowering of human capacities. Someone in his thirties, forties, or fifties was a fully developed person – a norm against which childhood and youth, on one side, and old age, on the other, could be measured as deviations.” 
Oh, one might hear the term “middle age,” but it had no significance beyond a mere chronological measure. The notion that middle age would one day be a source of identity, shaping the way we envision our inner lives, view our family and professional obligations, and locate ourselves in the community and culture, would have been as alien to Cole as iPads and airplanes. Aging in his day was still conceived of primarily as a spiritual progression. In each of Cole’s landscapes, an angel hovers above the traveler’s boat on the River of Life, shining a light through blackened clouds during Man’s rough sailing or closely guiding Old Age towards heaven, his eternal home. The idea of middle age -- as a discrete category of development with unique characteristics and needs, or as a subject that merited reflection and analysis – followed the shift of authority away from faith and towards science. Cole would not have found essays on the topic in periodicals and books. Musicians, poets and novelists did not use their artistry to detail the aspects and effects of middle age. Correspondents and diarists did not generally write about being middle age in their letters or journals. Scholars did not devote years to its study. Advice manuals did not refer to behavior, clothes or activities that were appropriate for people in their middle years as opposed to any other time of life. There were no medicines, organizations, leisure activities, or treatments designed specifically for people in their middle decades. The word “midlife” first appeared in the dictionary only in 1895, when Funk and Wagnall’s defined it as “the part of life between youth and old age.”
As Howard Chudacoff concludes in his study of aging in America, How Old Are You?: “Before the 20th century, middle age was seldom considered as a separate time of life.”