What is the second most important tool according to King?

King believed that grammar is the second tool a writer should have. He believes that a thorough reading of Strunk and White's Elements of Style should be sufficient to inform the writer of simple grammar rules that he should follow. King stresses that the writer should not study the rules of grammar at length. King did not want his readers to become fanatical about grammar. He wants them to be aware of the rules of grammar and observe them in most of their writing, but he also feels it is okay to break the rules occasionally.