Sometimes you don't need to write a lot to express a feeling. This category is for sad poems when just a few lines will do. Feelings are not complex. When we allow ourselves to feel them in a pure undiluted way, we often begin the process of releasing pent up sadness. When you want to tell the story and the reasons behind the feeling, that will often turn into a longer poem. Both of these styles of telling are equally valid. It is simply a matter of what needs to be expressed in the moment.