7. Why do you think that the author William Zinsser believes professional writers focus so much on
revision and rewriting – and why does he consider it to be the essence of his
profession?

The author believed that professional writers revise and rewrite their sentences because the first draft is usually written in emotions and thus needs to be revised to correct any error.

Zinsser considered rewriting to be an essence of his profession because it helps him to correct the errors in doing so.

Explanation:

'On Writing Well'  is a book written by William Zinsser. The book talks about the skill of writing and how to develop and polish that skill.

In his book, he asserted that revising and rewriting is something that most writers do. He believed it because rewriting helps a writer to correct any information left out, or to add any vital information in his writing.Or, to correct any grammatical error in the writing.

He perceived that revising and rewriting is an essence of his profession because it help him to correct any errors in his profession of writing. Rewriting and revising enhance ones written work and helps to bring the best out to his/her  readers. He asserted that first draft of the writing is usually written in emotions or out of the flow of thoughts that comes to our mind.