Paul Rouzer :: Almost all Chinese poems are written in couplets. That is, every two lines tend to form a separate poetic idea or a separate statement. And these couplets basically form discreet ideas.
Consequently, when you read a Chinese poem, you're often very much aware of how ideas fall into this very set form. Each couplet following each couplet, each idea basically split off from the other idea.
Up until the Tang dynasty, couplets could be of any particular length. Poets
could write poems of only two couplets, they could write poems of sixteen
couplets, they could write poems of fifty couplets. There was no particular
rule telling them now long a poem could be. A poet basically expressed what
he wanted to express in a poem, and then he stopped.
In the Tang dynasty however, many experimental poets became increasingly interested in more strict rigid forms. And they developed a particular kind of verse that was an important, very important type of Chinese verse for the rest of the tradition. This was the so-called "regulated verse." A poem was basically confined to four couplets.