67. 蜀道难（李白）

主句在全诗出现三次：开头刚点出题目时就出现，中间写到子规啼夜月时出现，结尾侧身西望时又出现。三次的位置不一样：第一次是宣告，第二次夹在最长的句子里，是鼓动情绪，第三次收尾，是承认自己无力。李白不换字，连语气助词都保持原样，靠的是前后语境的差别来给它不同的分量。这种重复有个实际作用：全诗二十四句，段落之间跳得很厉害，从天上的星宿跳到地上的漩涡，再跳到朝廷的政治，有一句固定的话来回，读者才不至于丢掉方向。乐府本来就讲究复沓，李白把它用在了长篇上。

The main sentence appears three times: at the opening just after the title is named, in the middle at the cuckoo crying in the night moon, and again at the close as he turns to look west. The three positions differ. The first is a declaration; the second sits inside the longest line and stirs feeling; the third closes the poem and admits helplessness. Li Bai does not change a character, keeping even the tone particle, and relies on the shift in context to give it different weight. The repetition does practical work too: the poem runs twenty-four lines and jumps hard between sections, from the constellations overhead to whirlpools below to court politics, and one fixed sentence recurring keeps the reader from losing the thread. Yuefu has always favored refrain; Li Bai applies it to a long piece.

全诗的空间一路往下走：先是噫吁戏的一口气，然后是蚕丛鱼凫的四万八千年，再是摸得到的参星井宿，接着跌到冲波逆折的回川、万壑雷的瀑布，最后落到剑阁和一个守关的人。前大半写的是自然的险，到最后三句突然变成政治：守关的人若不是亲信，就会变成豺狼，于是「朝避猛虎，夕避长蛇」。李白没有解释这个转折，但两段是相关的——自然再险，还有一个守得住的说法；人若不可信，连关都守不住。这也是《蜀道难》历来注家争论最多的地方，有人说是送友人入蜀，有人说是忧虑藩镇，李白自己没交代。

The poem moves steadily downward through space: first the single breath of yi xu xi, then the four hundred and eighty centuries of Can Cong and Yu Fu, then the constellations Shen and Jing within reach, then down to the churning whirlpools and the thunder of ten thousand gullies, and finally to Jiange and one man holding a pass. Most of it writes the danger of nature; the last three sentences turn suddenly political: if the one who holds the pass is not your own, he turns into wolf and jackal, and so by morning you avoid the tiger, by evening the serpent. Li Bai does not explain the turn, but the two parts are connected — nature may be perilous, yet it can still be held; if a man cannot be trusted, not even the pass can be held. This is also the most argued point among commentators: some read the poem as seeing a friend off into Shu, some as anxiety about military governors, and Li Bai himself says nothing.

「噫吁戏！危乎高哉！」六个字，前三个是叹词，后两个是形容词，都不是能作主语的东西。一直要等到「蜀道之难难于上青天」，才有了一件可以谈的事。这个开头的作用是把人先放进一个反应里：还没看见山，先听见有人被吓了一跳。乐府诗常常这样起头，像《箜篌引》的「公无渡河」，先给声音再给事。李白把这套用法推到极处，全诗第一句连一个实词都没有。后面因此可以随便铺排，因为读者已经被定在了「听人喊」的位置上。

Yi xu xi! How perilous! How high! — six characters: three interjections and two adjectives, none of them capable of being a subject. It takes until the road to Shu is harder to travel than climbing to the blue sky for there to be something to talk about. The opening works by putting the reader inside a reaction first: before the mountain is seen, someone is heard being startled by it. Yuefu poems often start this way, as the Konghou Yin begins with Do not cross the river — sound first, event after. Li Bai pushes the habit to its limit: the poem's first line contains no content word at all. Everything after can therefore sprawl as it likes, because the reader is already fixed in the position of hearing someone shout.