Today, we know exactly how rainbows are made. In the seventeenth century, the scientist Isaac Newton and the mathematician and philosopher Rene Descartes analyzed them very carefully. They concluded that rainbows were caused when sunlight was broken up as it passed through raindrops.

现在，我们已确切知道彩虹是怎样形成的。在十七世纪，科学家牛顿和数学家兼哲学家的笛卡尔，就非常仔细地分析过彩虹，他们断定-彩虹的形成是因为阳光穿过雨滴时被打散所致。

(短文节选,本篇始于：彩虹来自何方)