The definition of harmony is when two or more tones fit together in a pleasing combination of sounds.
Explanation:
This phrase is awkwardly put together and is not sure if it is explaining harmony or the definition of harmony. The problem with the main phrase <em>"harmony is when two or more tones fit together in a pleasing combination of sounds"</em> is repeated in this revision. You can't say <em>"Harmony is when"</em>, because harmony is not a moment in time. It might occur in a moment in time, though, which makes much more sense.
It is true that a well-written paragraph should be coherent and unified. These characteristic are some of the most important ones when it comes to writing essays.
