There can be little doubt that major portions of Gurdjieff's teaching are derived directly from yoga sources. He changed the language, but the understandings are fundamentally identical.
I thought it might be worthwhile to review some of the specific instances underscoring this fact.
Let's begin with the
classic yoga Sutra from the Upanishads recounting the tale of the horse, carriage, and driver. (Click the link to read it in its original.) This story is repeated no less than nine times in various places in the
three most well-known sources:
In Search of the Miraculous,
Beelzebub's Tales to his Grandson, and
Views From the Real World. (Once again, click the link to review the passages.)
In
Beelzebub, Gurdjieff furthermore saw fit to expand on the analogy until it filled a colorful nine pages; and that, at the very end of the book, where he felt it necessary to append an editorial with a number of very specific references, including
one which is obviously about the six lower chakras, which he called "receivers of vibrations of different qualities."
His extensive chapter on the chemical factory includes
obvious and unambiguous references to Prana, which is concentrated through breathing in the practice of Pranayama. And the rest of the book this particular reference comes from is rife with yoga concepts, including the idea of the centers, which has just about everything to do with yoga's idea of chakras. The
correlations between the yogic system and Gurdjieff's own are extensive.
There can be no doubt that Gurdjieff considerably expanded on the ideas in yoga, especially with his introduction of the ancient symbol that used to connect all of the ideas in the yoga schools,
the enneagram. The importance of this diagram can't be understated, since study in depth will reveal that the diagram is
everything he said it was. Nonetheless, the ideas presented by his system and this diagram are complex, and an entry-level understanding of the basic concepts surrounding the diagram, the ray of creation, the 27 types, and so on represents only a scratch on the surface. Remember, ancient schools (one of Gurdjieff's numerous examples is the "Adherents of Legominism" in ancient Babylon) studied these ideas for thousands of years.
My own impression, shared by some scholars, is that almost all "modern" religions — and by modern, I mean any contemporary religions which have left discernible traces in the art and writings of ancient societies — are descended from a prototypical,
Ur- religion, a
root form of yoga, which was practiced somewhere between 5,000 and 8,000 years ago or more in the civilizations of Turkey and countries lying to the east, most probably in the very ancient
Indus River Valley civilizations, of which relatively little is known.
By the time we encounter the first very large examples of organized religion in major civilizations such as Babylon and Egypt, it had begun to separate from its original traditions and, as both Gurdjieff and Ouspensky maintained, degenerate. That is to say, its ideas had become fragmented and were no longer intact. Certainly, this is the context that
Beelzebub's Tales to His Grandson presents religion in; and it need hardly be important, whether or not a civilization called Atlantis actually existed or was submerged under the ocean. We can fairly say that the story of Atlantis ably serves, in
Beelzebub, as an allegorical vehicle on several different levels; one might also say that today, the myth serves a far greater purpose than any reality could.
In any event the point is that what we know of history emerged from well-developed and sophisticated civilizations with intricate philosophies and detailed understandings of both the natural world and man's nature.
To believe that these understandings only emerged recently — by recently I mean within the last 3,000 to 4,000 years—starting with Egyptian and Babylonian civilization is to vastly underestimate the ability of earlier cultures to think, and to question their existence. One of the conceits of modern civilization is to imagine ourselves as intellectually superior to earlier cultures; whereas the exact opposite may well be true.
So yoga, as a practice, probably underlies the origin of Egyptian religion, Judaism, Christianity, Sufism, Islam, Hinduism, and Buddhism, all of which emerge on the scene much later than the original civilizations in which yoga practices are clearly recorded in art. As such, it does represent what one might call the "esoteric core" of all religions, which — not coincidentally — is what Gurdjieff said his teaching was.
As if all of that weren't enough, we are left with the following quote from the man himself:
"The fourth way is the way of “Haida-yoga.”... and there's yet a bit more to come on this subject.
I respectfully hope you will take good care.