Original Thesis was written in 1948 (his 1st book on Dianetics) but not published for wider circulation until later.
There was a first manuscript - which was never a book - and it had several proposed titles, most notably the title
Excalibur, from 1938
.
Some of the theory part of "Book One" (DMSMH) came from
Excalibur.
Other parts of DMSMH were derived from Hubbard's experiences with self induced (self drugged or natural sleep) unconscious states during self-hypnosis - done with a sound recorder, with a recording of his own voice proclaiming "affirmations."
Other parts of DMSMH theory were derived from Hubbard's experiences as a do-it-yourself abortionist and avid wife beater.
The general idea of prenatal memory was derived from earlier published speculations by others.
Language (words) as a source of social and psychological problems had been popularized by Korzybski in his General Semantics.
The subject of bringing relief from symptoms by uncovering buried trauma - called abreaction - had been around for decades.
Hubbard "P.T. Barnum-ized" it, with promises of becoming a kind of superman, and added the manipulative mechanism of "survive!" by announcing that Mankind's survival depended on Dianetics.
Original Thesis was a short manuscript, and not a little book until years later.
There are actual books that have footnotes that are longer than either
Original Thesis or
Evolution of a Science.
The magazine article,
Evolution of a Science, also became a little book years later.
Late 1960s edition with cover that Hubbard believed to have hypnotic power.
Scientology is like a car that vibrates but cannot be driven anywhere. To a Scientologist, simply vibrating is tremendously impressive and sufficient to say, "Scientology works!" Arguing with Scientologists about this is usually a waste of time.