“One of the seats of emotion and memory in the brain is the amygdala, he explained. When something threatens your life, this area seems to kick into overdrive, recording every last detail of the experience. The more detailed the memory, the longer the moment seems to last. "This explains why we think that time speeds up when we grow older," Eagleman said--why childhood summers seem to go on forever, while old age slips by while we’re dozing. The more familiar the world becomes, the less information your brain writes down, and the more quickly time seems to pass.”

“The brain, he writes, is like Kublai Khan, the great Mongol emperor of the thirteenth century. It sits enthroned in its skull, "encased in darkness and silence," at a lofty remove from brute reality. Messengers stream in from every corner of the sensory kingdom, bringing word of distant sights, sounds, and smells. Their reports arrive at different rates, often long out of date, yet the details are all stitched together into a seamless chronology. The difference is that Kublai Khan was piecing together the past. The brain is describing the present—processing reams of disjointed data on the fly, editing everything down to an instantaneous now. How does it manage it?”

“It's perhaps not so much how your amygdala is tuned that makes you politically extreme, but that your intrinsic nervousness makes you more responsive to things that might seem to threaten your particular social world. Education probably plays an important role in dampening that response by allowing the brain's frontal lobes (where much of the brain's conscious work goes on) to counteract the emotional responses with a more considered view, so explaining why education is invariably the friend of liberal politics.”

“Maybe the more emotions a person experiences in their daily lives, the longer time seems to feel to them. As you get older, you experience fewer new things, and so time seems to go by faster.”

“Live as long as you may, the first twenty years are the longest half of your life. They appear so while they are passing; they seem to have been so when we look back on them; and they take up more room in our memory than all the years that succeed them.”

“Life seems to speed up as we get older because life gets less memorable as we get older.”

“He was glad some of the pain was fading, had already faded so much since the first year. But it seemed more to be a trade off: with the pain went details and memories. People had said, ‘Time heals,’ but he realized time didn’t heal, time just eroded and confused, and he didn’t think that was the same thing at all.”