“The word sadness originally meant "fullness," from the same Latin root, satis, that also gave us sated and satisfaction. Not so long ago, to be sad meant you were filled to the brim with some intensity of experience. It wasn't just a malfunction in the joy machine. It was a state of awareness– setting the focus to infinity and taking it all in, joy and grief all at once. When we speak of sadness these days, most of the time what we really mean is despair, which is literally defined as the absence of hope. But true sadness is actually the opposite, an exuberant upwelling that reminds you how fleeting and mysterious and open-ended life can be. That's why you'll find traces of the blues all over this book, but you might find yourself feeling strangely joyful at the end of it. And if you are lucky enough to feel sad, well, savor it while it lasts– if only because it means that you care about something in this world enough to let it under your skin.”