I gave a 10-year-old girl a unicycle for her birthday last week. I can never put into words the look on her face when she made, only an hour later, her first three cranks in a row before falling off (it took me 2 days to get that far in my early 30's). It is this type of experience that makes growing old worth the pain: to see the world through their eyes as though it were all new again (paraphrasing Virgil).