In your brain the down world is managed by a handful of chemicals—neurotransmitters, they’re called—that let you experience satisfaction and enjoy whatever you have in the here and now. But when you turn your attention to the world of up, your brain relies on a different chemical—a single molecule—that not only allows you to move beyond the realm of what’s at your fingertips, but also motivates you to pursue, to control, and to possess the world beyond your immediate grasp. It drives you to seek out those things far away, both physical things and things you cannot see, such as knowledge, love,
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