Coming of age in Paris
The existing literature treats the 40s as transitional. Victor Hugo supposedly called 40 "the old age of youth." In Paris, it's when waiters start calling you "Madame" without an ironic wink. The conventional wisdom is that you're still reasonably young, but that everything is declining: health, fertility, the certainty that you will one day read "Hamlet" and know how to cook leeks. Among my peers there's a now-or-never mood: We still have time for a second act, but we'd better get moving on it.
Paris -- the world's epicenter of existentialism -- isn't terribly helpful. With their signature blend of subtlety and pessimism, the French carve up midlife into the "crisis of the 40s," the "crisis of the 50s" and the "noonday demon" (described by one French writer as "when a man in his 50s falls in love with the babysitter").
The modern 40s are so busy it's hard to assess them. Researchers describe the new "rush hour of life," when career and child-rearing peaks collide. Today's 40ish professionals are the DITT generation: double income, toddler twins.