This sentence uses metaphor and exaggeration.
Source: Looking at Lushan Waterfall written by Li Bai, a great poet in the Tang Dynasty.
Original text: The incense burner in Rizhao produces purple smoke, and the waterfall hangs in front of Sichuan in the distance. The high bluff on the high cliffs, as if there were a few thousands of feet, people trance thought that the galaxy from heaven to fall into the world.
The incense burner peak glowed with purple haze under the sunlight, and a waterfall hung in front of the mountain like white silk in the distance. It seems that there are several thousands of feet waterfalls on the high cliff, which makes people think that the Milky Way has fallen from the sky to the earth.
Author's brief introduction: Li Bai (71-762), whose name is Taibai, was named Qinglian Jushi and Xianren, was a great romantic poet in the Tang Dynasty. He was praised as "Poet Fairy" by later generations, and was also called "Li Du" with Du Fu. In order to distinguish himself from the other two poets Li Shangyin and Du Mu, that is, "Little Li Du", Du Fu and Du Fu
according to the book of the new Tang dynasty, Li Bai is the ninth grandson of the emperor Xingsheng (Li Jue, king of Liangwu Zhao), and he is the same ancestor as the kings of Li Tang. He is cheerful and generous, loves to drink and write poems, and likes to make friends. Extended information
The incense burner in the poem, that is, the incense burner peak mentioned at the beginning of the first poem, "In the northwest of Lushan Mountain, its peak is round, and the smoke clouds gather and disperse, like the incense burner in Boshan Mountain" (the history of music "Taiping Universe"). However, when it comes to the poet Li Bai's pen, it becomes another scene: an indomitable incense burner, with clouds of white smoke rising slowly in Ran Ran, ethereal between the green mountains and the blue sky, and turned into a purple cloud under the irradiation of the red sun.
This not only makes the incense burner peak more beautiful, but also is romantic, creating an unusual background for the unusual waterfall. Then the poet turned his eyes to the waterfall on the mountain wall. "Looking at the waterfall hanging in front of the river", the first four words are the point. "Hanging in front of the river" is the first image of "looking", and the waterfall is like a huge white practice hanging high between mountains and rivers.
The word "hanging" is wonderful. It turns motion into stillness and vividly shows the image of a pouring waterfall in "looking from a distance". The first poem says, "Brave!" It is this "nature" that can "hang" this giant, so the word "hanging" also contains the poet's praise for the magical power of nature.
The third sentence also describes the dynamics of waterfalls. "Flying down three thousands of feet", a stroke, forceful every word. The word "fly" vividly depicts the scene of the waterfall spewing out; "Straight down" not only describes the high and steep mountains, but also shows the urgency of the water flow. The sky is straight down, and it is unstoppable.
However, the poet was not satisfied enough, and then he wrote a sentence, "Doubt is that the Milky Way has fallen for nine days", which really made him want to fall into the sky and astonish his soul. "Doubt is" is worth pondering. The poet clearly said it in a trance, and the readers know it is not, but they all think that it is only in this way that it is more vivid and realistic. The secret lies in the image that has been bred in the poet's previous description.
The towering incense burner peak is hidden in the clouds and mist. Looking at the waterfall in the distance is like flying down from the clouds and falling in the sky, which is naturally associated with a galaxy falling from the sky. It can be seen that the metaphor of "Doubt is the Milky Way setting for nine days" is strange, but it does not come out of thin air in the poem, but naturally emerges from the portrayal of the image.
It is exaggerated and natural, novel and true, thus arousing the whole article, making the whole image more colorful and magnificent, which not only left a deep impression on people, but also left room for imagination, showing the artistic style of Li Bai, which is "Wan Li falls down, and the final trend is still strong".
Reference: Baidu Encyclopedia-Wanglushan Waterfall