“我们几乎没有关于我们的日常生活理解。我们几乎没有想到那些产生阳光的机器，使生活成为可能。粘在地球上的重力，否则将我们旋转到太空中。或to the atoms that which we are made, and on who’s stability we fundamentally depend. Few of us spend much time wondering why nature is the way it is. Where the cosmos came from. Whether it was always there. If time will one day flow backward. Or whether there are ultimate limits to what humans can know. What is the smallest piece of matter. Why we remember the past and not the future. And why there is a universe."

• 卡尔萨根