勇气是人类文明亘古不变的主题，但是对勇气的系统性研究却是最近才开始的。什么是勇气？勇气从何而来？它在身体和大脑中是如何体现的？为何我们会对它如此之挚爱？没有恐惧感是不是件好事情呢？本文将一一予以解答。
In his 20 years as a firefighter and paramedic in Colorado Springs, Bruce Monson, 43, has had his little fist-bumps with death: a burning roof collapsing on top of him, toxic fumes nearly suffocating him.
在其作为科罗拉多斯普林斯（Colorado Springs）市消防员和急救人员的20年生涯里，43岁的布鲁斯·蒙逊（Bruce Monson）跟死神有过小小的亲密接触：一座燃烧的屋顶从他头顶坍塌，有毒气体几乎令其窒息。
Yet far more terrifying than any personal threats are what Mr. Monson describes as the "bad kid calls," like the one from a mother who had put her 18-month-old son down in his crib right next to a window with a Venetian blind and its old-fashioned cord.
但是比所有的个人威胁都要恐怖得多的，是被蒙逊先生描述为"捣蛋鬼电话"的，就像是一位妈妈打过来的电话一样，这位母亲把自己18个月大的孩子放到了婴儿床上，而婴儿床则正好靠近一个带有软百叶窗和老式绳索的窗户。
"The kid had grabbed the cord and gotten it twisted around his neck, and the mother came in and found him hanging there," said Mr. Monson. "I'm the first one in the door, she's in a panic, and she shoves the kid into my arms, crying, 'Please save him, please save him!' "
"小孩抓住了那条绳子，然后被绳子绕住了自己的脖子，接着母亲进来就发现他悬在那里了"，蒙逊先生说："我是第一个上门的，她还在恐慌之中，一把就将孩子塞到我手臂里，哭着说，'请救救他，快救救他！'"。