Poignancy, she told me, is the richest feeling humans experience, one that gives meaning to lifeand it happens when you feel happy and sad at the same time. Its the state you enter when you cry tears of joywhich tend to come during precious moments suffused with their imminent ending. When we tear up at that beloved child splashing in a rain puddle, she explains, we arent simply happy: Were also appreciating, even if its not explicit, that this time of life will end; that good times pass as well as bad ones; that were all going to die in the end. I think that being comfortable with this is adaptive. Thats emotional development.

Bittersweet by Susan Cain