Here's why:
* Metaphor: A metaphor is a figure of speech where a word or phrase is used to describe something else, creating a comparison without using words like "like" or "as."
* "Liquid ditty" compares the sound of the bells to a song (ditty) that is flowing like a liquid.
While the bells themselves are not liquid, the use of "liquid" evokes the smooth, flowing nature of the sound they create.
This metaphor helps create a vivid and evocative image of the bells' sound, contributing to the overall atmosphere of the poem.