The master essayist-doctor celebrates the tools of his literary trade--in this delightful etymological exploration of the English language. "In our backyard is a horse-chestnut tree the size of a church," Thomas begins. Two hundred years old, 120 feet high, this creation of nature can't help but evoke feelings of reverence and admiration. Imagine, suggests Thomas, asking a small child to invent a word for the tree. The word would most likely embody the emotion it inspires. Later the same word would be used to evoke similar emotions, and would be pummeled into varying shapes to represent related qualities and conditions such as vigorousness, youth, and eternity. Thomas' sheer pleasure in such a notion proves contagious as he flips through his well-thumbed American Heritage Dictionary and etymology books to find ancient links between "self" and "secure," "gorgeous" and "gargoyle," "repent" and "in a hurry," etc. More than a mere historical science, etymology is, in Thomas' admittedly unscholarly view, an enchanting window into the long-buried meanings still subtly at work inside modern words--meanings that add resonance and subtext to every conversation. In pursuit of poetic undercurrents, the author doesn't hesitate to depart from traditional Indo-European genealogies to speculate on, for example, the notion of a youngster inventing language by gazing at his twin miniature reflections in his mother's eyes and naming the dark mirrors "pupils"--small children. Such charming images are the mark of an infectious enthusiasm, and will surely tempt others to succumb.