Qualities of expression: Importance of unity

When writing, keep the whole, rather than the parts, in mind.

While other qualities are useful, unity of expression in writing is absolutely essential. The result, whatever the length, is a coherent whole that the reader can easily assimilate.

From Beginnings of Rhetoric and Composition, by Adams Hill:

Importance of unity

Every piece of writing should be a unit. 

A good writer sees his subject as a whole and treats it as a whole: he gives prominence to one idea, and groups other ideas round that one in such a way as to allow to each part the exact amount of space and the exact position it should occupy.

The more complex and varied the material, the greater the value of unity and the greater the difficulty in securing it; but unity in some degree is within the reach of every one who will work for it.

Unity in expression grows out of unity in thought: a writer who is in the habit of grouping in his mind things that belong together is more likely to form his sentences on a similar principle than one whose mind is a scene of confusion. Whoever, then, would secure unity in his language must have it in his thought.

One who aims at unity will not

1. put into one sentence ideas that belong in two or more,

2. scatter through two or more sentences ideas that belong in one,

3. confuse readers by allowing words to hang loose in a sentence

4. change his point of view without reason, or 

5. treat subordinate ideas as if they were of equal rank with the main idea.

Aim at unity both in substance and in form.