See, I think I know who Jacob and the Man in Black are, or at least what's going on with all the Egyptian stuff.
But first, we'll need to take a bit of a digression into comparative religion. Even if you don't watch Lost, I find this particular thread in western mythology pretty fascinating. It's going to be a long ride, though, so feel free to skip this post if you don't care about mythology or primetime fantasy series. I promise I won't be offended.
Let's start with the first words in the Bible:
In the beginning God created the heaven and the earth. And the earth was without form, and void; and darkness was upon the face of the deep. And the Spirit of God moved upon the face of the waters.
In the beginning, all that exists is the ocean. But in Biblical cosmology, the ocean isn't a benign geographic feature; it's the Deep. The Abyss. Tehom. The primordial chaos, incompatible with human life, from which comes destruction and death. In order to carve out a place of order where humans can live, God builds barriers to hold back the waters:
And God said, Let there be a firmament in the midst of the waters, and let it divide the waters from the waters. And God made the firmament, and divided the waters which were under the firmament from the waters which were above the firmament: and it was so. And God called the firmament Heaven...And God said, Let the waters under the heaven be gathered together unto one place, and let the dry land appear: and it was so...And God called the dry land Earth; and the gathering together of the waters called he Seas: and God saw that it was good.
Mankind lives in the only safe enclave in a cosmos of chaos, a tiny pocket of dry land in a cosmic ocean. When God destroys the world with Noah's flood, he doesn't simply create lots of rain--he pierces the barriers and lets the Deep in:
And it came to pass after seven days, that the waters of the flood were upon the earth. In the six hundredth year of Noah's life, in the second month, the seventeenth day of the month, the same day were all the fountains of the great deep broken up, and the windows of heaven were opened.
This is not an original Hebrew idea. The theme of the cosmic ocean of death and chaos being held back by the works of a sky god, making a place of order for humanity, is an old, old element of Levantine-region mythology. All the way back in Babylonia, the chief deity (generally Marduk, but the precise identity changed over time) slew Tiamat (believed by some to be cognate with Tehom), the primordial goddess of the chaotic sea:
And the lord stood upon Tiamat's hinder parts,
And with his merciless club he smashed her skull...
He split her up like a flat fish into two halves;
One half of her he stablished as a covering for heaven.
He fixed a bolt, he stationed a watchman,
And bade them not to let her waters come forth.
Tiamat was not a dragon or serpent (despite the modern pop culture association), but she gave birth to dragons. The association would later be cemented in the Ugaritic variation of the story, in which the storm god Baal Hadad battles and defeats Yam Nahar, the god of the primordial chaos, of rivers and the ocean, both in his anthropomorphic form and then as the seven-headed river serpent Lotan:
[Paraphrased, because the literal translation is pretty awkward in English]
And the weapon leapt from the hand of Ba'al,
Like a raptor from between his fingers. It struck the skull of Prince
Yam, between the eyes of Judge Nahar. Yam collapsed, he fell
To the earth; his joints quivered, and his spine shook...
Then Ba'al dragged him out, intending to dismember him...
|From General interwebs|
The story of the sky god crushing the skull of the serpent representing the primordial chaos seems to have been a pretty strong metaphor for civilization holding out against the chaotic world, because it hung on in the area for a very long time. There are even echoes of it in the Bible, where Lotan becomes Leviathan:
Thou didst divide the sea by thy strength: thou brakest the heads of the dragons in the waters. Thou brakest the heads of leviathan in pieces, and gavest him to be meat to the people inhabiting the wilderness.
Also as Rahab:
Thou rulest the raging of the sea: when the waves thereof arise, thou stillest them. Thou hast broken Rahab in pieces, as one that is slain; thou hast scattered thine enemies with thy strong arm.
|From General interwebs|
This story resonates through western mythology at least up to the myth of Zeus killing Typhon, and in my opinion even all the way up to Norse mythology, in which the ocean-spanning Jormungandr, the serpent whose rising at Ragnarok poisons the world, is slain by a blow from Thor's hammer.
What does all this have to do with Lost? My Grand Unified Theory of Lost is that Jacob and the Man in Black are these mythological archetypes: the spirit of order, and the spirit of chaos, and that if they weren't literally the primordial sky-god and chaos-serpent, they were interpreted that way by the ancient Egyptian settlers on the island, who applied their version of the myth: the nightly battle between the sun god Ra and the subterranean river serpent Apep.
The ancient Egyptians were obsessed with order, which they summed up (and even personified) as the concept of Ma'at. Ma'at--both the concept and the goddess--was the combined ideals of Egyptian society: law, light, authority, truth, balance, justice, constance... Order in general, which stood in an eternal struggle against the chaos of the uncontrolled, barbaric world outside Egypt. The chaos serpent myth was an outstanding fit for the Egyptian worldview, and they took it a step further: the chaos serpent hadn't been defeated by the sky god to make the world safe for civilization; the sky god continued to battle the serpent every night for eternity, the fate of civilization hanging in the balance every single time.
Every day, Ra rode with Ma'at in his celestial boat across the sky from east to west, then descended into the underworld of Duat to journey back to the east for the following day's journey. But while sailing along the rivers of the underworld, Ra and his entourage--a bodyguard of gods along to protect him--would be attacked by Apep, the great snake who embodied evil, darkness, and chaos--the anti-Ma'at--who would try to overcome and devour him. Ra and his allies would defeat Apep and finish their voyage, but their victory wasn't seen as at all certain; every night's journey was a terrible risk to the order of the universe. Egyptian priests performed symbolic magic to weaken Apep, ritually mutilating and destroying wax models of him. Depictions of Apep were usually drawn with him injured or subdued, so as not to add to his power. The dead were sometimes buried with spells made to weaken him, to be used when their souls reached the underworld.
|From General interwebs|
The Egyptian version of the chaos-serpent myth--a being representing order locked in a constant struggle (through his supporters) with a being representing chaos, with the future of humanity on the line if he ever fails--is a pretty good fit with the relationship between Jacob and the Man in Black, as it's been presented. And there's some evidence in the show that, at the very least, the Egyptian islanders may have interpreted them this way, and Jacob's adopted their interpretation.
First, the "domains" of the two are closely associated with the sky and the underworld. Jacob's key domains are the temple (built in the form of a sky-reaching pyramid or ziggurat) and the lighthouse (a high place and a source of light). The Man in Black's key domains are a cave by the ocean, and the tunnels under Jacob's temple. These were obviously constructed for him, as there are perforated vents for him to pass through, and a relief depicting him in his smoke form sitting with the underworld-god Anubis (with two snakes nearby, perhaps coincidentally).
|From General interwebs|
And the smoke monster generally appears in a long, serpentine form, snaking its way between trees or around corners. It's about as close as the producers could reasonably get to having the Man in Black turn into a giant snake before it became really literal and probably a bit silly.
The broken statue on the island was once an enormous effigy of Taweret, a fairly obscure Egyptian deity mostly notable for her patronage of childbirth (another theme on the island), and--in early myths, before Set replaced Apep as the embodiment of evil--as the consort of Apep. According to Wikipedia (where the claim is uncited, so grain of salt, grain of salt):
Ultimately, although only a household deity, since she was still considered the consort of Apep, Taweret was seen as one who protected against evil by restraining it.
Jacob, at least seems to embrace an identification with Ra. His tapestry uses one of the artistic conventions of the reign of Akhenaten, rays of the sun ending in hands, symbolizing the influence of the sun god Aten (an aspect of Ra) on the affairs of the world. In Jacob's tapestry, unlike in original egyptian art, the hands of Ra are reaching down to touch individual people, just as Jacob did with the candidates. Incidentally, the tapestry also shows boats on the ocean, another aspect of the island's history that Jacob seems to be in charge of.
|From General interwebs|
Am I just indulging in primate pattern-making, cherrypicking details and making them fit my assumption? Maybe. There are some things that don't add up. Like why would the island's Egyptian settlers make a home for Apep under the temple of Ra? And what's up with the Man in Black being able to read people's past and take the forms of the dead (a much better match for Anubis, for example). I dunno. But the Lost writers, if nothing else, are extremely well read, and there's a good chance they've come across the chaos serpent archetype at some point. I hope it was at least part of their inspiration.