Image refers to the artistic image materialized or solidified by the unique aesthetic activities of the creative subject, which is the organic integration and unity of subject and object, mind and matter, meaning and image; It is the product of the fusion of subjective feelings and objective images.
The ancients were good at using homophones to express their feelings, and the pronunciation of "Liu" was similar to that of "Liu", so the ancients used "Liu" to express their thoughts about people who were about to leave. Because willows produce a lot of catkins in spring, "catkins" and "lines" are homophonic, so poets always express their carefree thoughts through catkins.