In Zhang Ji's Qiu Si ... Autumn wind is invisible ... Why is the word "see" used in the poem? How to understand this?

Qiu Si, a native of Luoyang, saw the autumn wind. He wanted to find a writer to write a book. When the letter is written, I am worried that I have not finished what I want to say; When the messenger started, he opened the envelope and gave it to him. Please write down the poem next time you ask, so that we can answer it easily! )

Here, the author uses the technique of "synaesthesia" (visual touch synaesthesia). The advantage of this writing is to turn the bleak autumn wind that the author feels into a real thing, show it to readers, and deepen their feelings about the autumn wind. In this way, the author can outline the sad atmosphere of autumn in front of readers, thus laying the groundwork for the author to write his deep thoughts about his hometown.