The human brain weighs three pounds. It is the size of a softball, and yet with it we have the capacity to learn something new every second of every minute of every hour of every day for the next three hundred million years. God has created us with an unlimited capacity to learn. What that tells me is that we ought to keep learning until the day we die.

Leonardo da Vinci once observed that the average human "looks without seeing, listens without hearing, touches without feeling, eats without tasting, inhales without awareness of odor or fragrance, and talks without thinking." But not da Vinci. The quintessential Renaissance man called the five senses the ministers of the soul. Perhaps no one in history stewarded them better than he did. Famous for his paintings The Last Supper and Mona Lisa, da Vinci trained himself in curiosity. He never went anywhere without his notebooks, in which he recorded ideas and observations in mirror-image cursive. His journals contain the genesis of some of his most ingenious ideas—a helicopter-like contraption he called an orinthopter, a diving suit, and a robotic knight. While on his own deathbed, he meticulously noted his own symptoms in his journal. That's devotion to learning. Seven thousand pages of da Vinci's journals have been preserved. Bill Gates purchased eighteen pages for $30.8 million a few decades ago.