On April 6, I began the revision, and on May 25, 1949, I finished it and retitled it Pebble in the Sky. On May 29, Doubleday accepted it, and I had to grasp the fact that I was going to have a book published.

 But even as I struggled with that, another change was taking place simultaneously.

 There was still the matter of a job. All the time I was working for Professor Elderfleld, I was still searching for one that I could take after that temporary position reached its natural end in May 1949. I was having no success at all.

 But then, on January 13, 1949, Professor William C. Boyd of Boston University School of Medicine was visiting New York, and we met.

 Professor Boyd was a science fiction reader of long standing and had liked my stories. For a couple of years we had been corresponding and we had grown quite friendly. Now he told me that there was an opening in the biochemistry department at his school and would I be interested? I was interested, of course, but Boston is twice as far from New York as Philadelphia is, and I hated to leave New York again.

 I refused the offer, but not very hard.

 And I continued to look for a job, and I continued to fail.

 I therefore reconsidered my refusal of the position at Boston University School of Medicine and wrote a letter to Professor Boyd, saying that perhaps I might be interested, after all.

 On March 9, 1949, I traveled to Boston for the first time in my life (on a sleeper - but I didn't sleep). I met Professor Burnham S. Walker, head of the department of biochemistry, the next day and he offered me a position on the faculty at five thousand per year. I saw no way out of my jobless dilemma but to accept.

 Did I have to? Was there no chance that I might have made my living as a writer?

 How could I honestly come to a decision that I could? In mid-1949, I had been writing for exactly eleven years. In all that time, my total earnings had come to $7,821.75, averaging a little over $710 per year, or $13.70 per week. In my better years, such as the seventh (mid-1944 to mid-1945, when I had sold four stories, including 'The Mule'), I had earned $1,600, and in the tenth and eleventh together I had earned $3,300. It looked as though, even in good years, I could not count on much more than thirty dollars per week, and that just wasn't enough.

 Of course, now that I was going to be publishing a book - But books were unknown quantities. Besides, the book sale had come too late. By the time Bradbury accepted Pebble in the Sky, I was committed to the new job, and two days later, on June 1, 1949, I left for Boston.

 It is at this point I must come to a halt, for the multiple changes put a final end to the first stage of my writing career.

 I had left Campbell, this time forever. Oh, I saw him occasionally, and we corresponded, but the steady drizzle of near-weekly visits was never to take place again. Though I wrote for him and continued to publish in Astounding, new magazines appeared, including The Magazine of Fantasy and Science Fiction in 1949, Galaxy Science Fiction in 1950, and others. My market broadened, and the word rate went up still further, to three cents and even four cents a word.

 The appearance of my first book, Pebble in the Sky, on January 19, 1950, introduced a new dimension to my self-image, to my prestige in the field and to my earnings. Other books followed - some new novels, some collections of older stories.

 My position at Boston University School of Medicine led me to publish non-fiction. The first attempt was a textbook for medical students called Biochemistry and Human Metabolism. This was begun in 1950 in collaboration with Professors Walker and Boyd. It went through three editions and, though rather a failure, allowed me to discover that I enjoyed non-fiction writing at least as much as fiction writing and helped me start on a new phase of my writing career.

 With all this taken into account, it is not surprising that my earnings as a writer began to rise rapidly almost as soon as I came to Boston. By 1952 I was making considerably more money as a writer than as a professor, and the discrepancy grew larger - in favor of writing - each succeeding year. By 1957, I'd decided (still somewhat to my surprise) that I had been a writer all along and that that was all I was.

 On July 1, 1958,1 gave up my salary and my duties but, with the agreement of the school, kept my title, which was then Associate Professor of Biochemistry. I keep that title to this day. I give an occasional lecture at the school when asked to do so, and I also lecture elsewhere when asked to do so (and charge a fee). For the rest, I became a full-time free-lance writer.

 Writing is easy now, and is ever more satisfying. I keep what amounts to a seventy-hour week, if you count all the ancillary jobs of proofreading, indexing, research and so on. I average seven or eight books a year, and this book, The Early Asimov, is my 125th book.

 And yet, I must admit there has never been, since 1949, anything like the real excitement of those first eleven 'Campbell years,' when I wrote only in my spare time, and sometimes not even then, when every submission meant unbearable suspense, when every rejection meant misery and every acceptance ecstasy, and every fifty-dollar check was the wealth of Croesus.

 And on July 11, 1971, John Campbell, at the still-early age of sixty-one, while watching television, died at 7.30 p.m. quietly and peacefully, without any pain at all.

 There is no way at all to express how much he meant to me and how much he did for me except, perhaps, to write these books evoking, once more, those days of a quarter century ago.