I am already old—in my early 60s, if you must know—so Hershfield furnished me not only with an image of myself in my 80s (complete with age spots, an exorbitantly asymmetrical face, and wrinkles as deep as a Manhattan pothole) but also with an image of my daughter as she’ll look decades from now. What this did, he explained, was make me ask myself, How will I feel toward the end of my life if my offspring are not taken care of?

which is easy to recognize when the question is thrust away from the present. Asked whether they would take $150 a year from now or $180 in 13 months, people are overwhelmingly willing to wait an extra month for the extra $30.