I suppose I explain iambic pentameter, stressed and unstressed syllables, but it happens naturally as we speak, so it's not horribly necessary.

I think that it is most important when writing to finish your idea. If it's all fragmented, or fragmented without a point, it piece seems empty and lackluster.

The second most important thing is emotion. I read a piece from a guy I know, great words, great rthythm, complete thoughts and everything... But it was told in a narrative style and lost all its power. Write like you are talking to someone, not reflecting in a diary. Assert your thoughts. Write to kick the reader/listen in the face, not drown them in something that actually has potential. This all relates to passive voice.

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