Mark Twain is an icon. No less a personage than William Faulkner called him “the father of American literature.” Most likely you had to read one or more of his books when you were in school. Huckleberry Finn as assigned to me in high school and then twice in college. Twain also wrote short stories and articles. So he had lots of experience to draw on when he said this.
“The time to begin writing an article is when you have finished it to your satisfaction. By that time, you begin to clearly and logically perceive what it is you really want to say.”
If you want even more writing advice from writers, check out Jon Winokur’s blog, “AdvicetoWriters.”
Mr. Clemens and Mark Twain: A Biography by Justin Kaplan