“With the success of my first story, l decided to make writing a career, though I was canny enough not to give up my job. But the job did not pay expenses and we had a recurrence of great poverty, sustained only by the thread of hope that I might make a living writing fiction. I cast about for a better job and landed one as a department manager for a business magazine. While I was working there, I wrote Tarzan of the Apes, evenings and holidays. I wrote it in longhand on the backs of old letterheads and odd pieces of paper. I did not think it was a very good story and I doubted if it would sell. But Bob Davis saw its possibilities for magazine publication and I got a check … this time, l think, for $700.”

How I Wrote the Tarzan Books (1929)