A well-known Japanese poet was asked how to compose a Chinese poem.
"The usual Chinese poem is four lines," he explained. "The first line contains the initial phrase; the second line, the continuation of that phrase; the third line turns from this subject and begins a new one; and the fourth line brings the first three lines together. A popular Japanese song illustrates this:
Two daughters of a silk merchant live in Kyoto.
The elder is twenty, the younger, eighteen.
A soldier may kill with his sword,
But these girls slay men with their eyes."
It's always been about form.