Looking Closer at How The Abominable Bride Foreshadowed and Can Be Used to Chronologically Decode Series 4:
In TAB, after being introduced to the Ricoletti case via the mystery of the missing corpse, Sherlock is haunted by a larger mystery going on, referring to "deep waters". He later returns to it when Lestrade comes to him with another murder. When speaking with Lestrade, Sherlock refers to trying understand the "obliquity of the ecliptic", a mathematical equation that describes the rotation of the earth around the sun, which he doesn't know already because he has to prioritize his set of knowledge. Lestrade insists that the Bride continues to rise and will murder again. In TST, after being introduced to the A.G.R.A. case via the missing Thatcher bust, Sherlock is haunted by a larger mystery going on, which he experiences via premonitions of water. He later returns to it when Lestrade comes to him with another break-in. When speaking to Mycroft, Sherlock describes his premonitions as a "movement of the web", made up of all available data of billions of lives on earth, no longer needing to prioritize what knowledge is important. Mycroft insists that the consequence of having that knowledge is like the merchant trying to outrun Death in his Samarra story. Both Sherlock and John are ruminating on the inevitability of death, but are doing so in very different ways. While Sherlock is looking in his dream for a way to escape Moriarty, John is writing his story to retroactively justify and cover up Mary's murder. [Continue below the cut for more ➤] See also: John is the sun, the stage is set, that wasn't the final problem.
After the opening sequence of TAB establishes the status quo of Sherlock's dream world, he begins planting seeds of conflict for things he wants to resolve based on what he's facing in the real world; the present threat of Mary and the eventual return of Moriarty. Watson and Mary begin arguing over how she doesn't ever see him because he keeps being pulled on Sherlock's adventures, which Sherlock finally undercuts with "Enough!", continuing with:
The stage is set, the curtain rises. We are ready to begin. Begin what? Sometimes to solve a case, one must first solve another. Oh, you have a case, then, a new one? An old one, very old. I shall have to go deep. Deep? Into what? Myself.
This description of the case taking him "deep" is later referenced by Sherlock as "deep waters", after Watson asks him his theory on the Ricoletti case. At this point in the episode first-time viewers don't know that we're in his dream world, and that this isn't just about the case being meaningful to his character, but that it's entirely constructed and informed by his biases. The meaning isn't particularly subtle either way; in order to solve the case, he has to be honest and face whatever's troubling him, but it becomes much more layered knowing that he's trapped in his own creation. What makes it even more complex is the way this echoes in the next series.
In TST, the post-title opening sequence contains a scene completely unlike anything else in the show; a narration by Sherlock. He recounts the story of the merchant in Samarra while the camera lingers over long, vividly blue shots of the London aquarium, the site of the episode's eventual showdown with Vivian Norbury ending in Mary's death. This water motif returns later when Sherlock first notices the marked spot of the missing Thatcher bust at the Welsborough estate during an unrelated case, where he has what looks like a revelation, with projections of water flooding the room and beaming onto his face.
Shortly after he goes to speak with Mycroft, where he asks if there's any connection between Moriarty and Thatcher; a completely ridiculous question that on its face should be dismissed. But Sherlock is insistent as he experiences the same sensation of water, lost in thought:
There's something important about this. I'm sure. Maybe it's Moriarty. Maybe it's not. But something's coming.
Mycroft then says what viewers are asking at this point: "Are you having a premonition, brother mine?"
It's essentially a supernatural vision; nothing like has ever happened in the show before. There is absolutely no surface connection between Thatcher and Moriarty, there will never one, and the connection to Mary he discovers later is entirely coincidental. He has no reason to respond to noticing the table scratches of a missing bust like this; there is quite literally nothing for Sherlock to have possibly deduced at this point in time, so Mycroft's description is entirely correct. It is a premonition of something else coming.
In TAB, Sherlock imagines months going by as he keeps trying to put off the Ricoletti case, until Lestrade comes to him with another murder, a threat to himself and John that he can't ignore any longer. But Sherlock tries to interrupt Lestrade by saying he's learning about something of "supreme importance". When an exasperated Lestrade asks what it is, what could be more important, Sherlock says he's trying to understand the "obliquity of the ecliptic"; the angle between the earth's axis and its orbital plane. The ecliptic effects how the earth experiences seasons, as it informs the earth's rotation and journey orbiting around the sun.
This gets a direct followup minutes later, the literal next scene, when the transition shows a spinning globe over Sherlock rotating around John, who's been associated with the sun since the show's beginnings.
In TGG, Sherlock admits that he doesn't remember that the earth rotates around the sun, because he's "deleted" it from his mind:
Sherlock: Listen. This is my hard drive, and it only makes sense to put things in there that are useful... really useful. Sherlock: Ordinary people fill their heads with all kinds of rubbish, and that makes it hard to get at the stuff that matters. Do you see? John: But it's the solar system! Sherlock: Oh, hell! What does that matter?! So we go round the Sun! If we went round the Moon, or round and round the garden like a teddy bear, it wouldn't make any difference. All that matters to me is the work. Without that, my brain rots.
Later in the episode, knowledge of the solar system figures not just into solving the Van Burn supernova present in the forgery painting, but at the astronomy show, where John is lit by the sun. There are many other references across the show to John being associated with not just the sun, but fire and heat; Moriarty's "I will burn the heart out of you", "Amazing how fire exposes our priorities", "conductor of light", "Is the lamp still burning?", etc. In TEH, John is trapped in a bonfire and saved by Sherlock before the transition places him over the sun on Baker St.
Sherlock describing the earth's rotation around the sun as "supreme importance" is him placing trying to understand his relationship with John, the status of which is incredibly thorny after the events of HLV, above trying to figure out the threat of Mary and Moriarty, which ironically is what got both of them this deep into this mess: because instead of confronting both of them by communicating his feelings with John, Sherlock has tried to treat them separately like spinning plates, thinking he has to protect him first. This is the central conflict of TAB in particular.
In contrast, TST on the surface is not about John and Sherlock's relationship at all. Much of the time, they barely interact with each other.
It's not just the dramatic focus that's off; in TST, Sherlock describes his premonitions as "just a movement of the web", and that the web is made up of "strands" of billions of lives. This isn't a complete departure from earlier series; Moriarty has long been described as a spider. But what is completely different is how Sherlock's deduction works – he suddenly has no lack of access to any set of knowledge. He's plugged into the entire world. He no longer has to prioritize what to remember and what to "delete". He can pick up an instant connections with no relation at a whim.
The significant difference between these two episodes being: TAB was in Sherlock's dream, which is why he knew what was coming. TST is not; it's John's story. Everything about TST is informed by his biases and constructed around covering up Mary's murder.
The visions of water, the premonitions, the opening narration, the future being "entirely calculable" and "as inevitable as mathematics" (and of course everything else about it; the aquarium setting, the gathering of witnesses and John's convenient absence, Sherlock goading her on and accentuating his old character flaw, Mary leaping in front of the bullet, etc.), is all built towards characterizing her death as an unavoidable tragedy.
John is retroactively guiding him towards the conclusion he needs him to reach for the story to work, assuming (correctly, given the reception of series 4) that the audience will take Sherlock's powers of deduction for granted because of his reputation and won't look closer at proving that any of this really happened.
In TAB, Lestrade berates Sherlock for calling the Ricoletti case "boring", saying there have been five more murders, rice on the floor like at a wedding (which Sherlock recently attended), "You" scrawled on the wall in blood, and that the bride has risen again and can't be ignores.
In TST, Mycroft says Sherlock's description of inevitability reminds him of the merchant from the Samarra story, who flees to another city hoping to avoid Death, told in Sherlock's opening monologue. This episode is the first time it's been mentioned, but it was actually first set up in TEH with Sumatra Rd., the location of a derailed subway car.
Both Sherlock and John are trying to escape from death in their respective stories. Sherlock's version of learning to eventually confront what he's scared of assumes the form of dream logic; constructed and ever-shifting scenarios designed to allow him to go deeper into himself. "Sometimes, to solve a case, one must first solve another".
Both of their stories struggle with not being impenetrable from reality. John's situation is similar: in order to escape from the blame of Mary's death, he has to write a cover story that absolves him of the crime, but like Sherlock trying to confront Moriarty alone, it's ironically what's trapped him and made him vulnerable to Mary's inevitable return. Similar to Sherlock, John is also trapped by separating his feelings for Sherlock from facing Mary, and prioritizing trying to explain his relationship with him over confronting the underlying issue, resulting in them being frozen in time. The real solution to all this, and to breaking the cycle of the Samarra story, has already been foreshadowed in Sumatra Rd., where both of them will have to confess how they feel.
At this point in the timeline however, both characters are far from that.
Sherlock will come that realization at the end of the episode when they confront Moriarty together, and will work with John to take Mary down in the next episode, but still still refrain from telling John the most important thing. John, however, will continue his downwards spiral, both in his story and in the real events behind series 4, culminating in TFP with the false inversion of Sumatra Rd., where similar to TEH, Molly will be forced to confess to loving Sherlock under threat of a bomb (unknowingly to Molly).
Sherlock learns that the bride doesn't have to rise again; that people can change, cycles can break, and the future is not inevitable. It's not just the stupid visions that make it incredibly clear that this version of Sherlock is filtered through John; it's that suddenly in TST, Sherlock believes in inevitability again. He believes in predestination.
This is naturally explained by John simply not knowing what Sherlock experienced in TAB; this can also be seen in how John characterized both Molly and Ms. Hudson. But just in terms of visual dissonance, tonal incoherence and completely absurd visuals, the contrast between Sherlock's "deep waters" in his dream vs. how John's version experiences those "deep waters" in his story is one of the most obvious.
The parallel between these two scenes is completely on purpose: the continuation of the water motif from TAB to TST is designed to pass a glance from general audiences, but stick out when paying attention. It's designed to look as if it's a natural continuation when it isn't; it's a complete contradiction.
This method returns in TLD and TFP; both episodes use water motifs that culminate in the ending of TFP, where Sherlock is experiencing these premonitions because of a repressed memory.
During this sequence, the water motifs in series 4 are connected to their presence in previous series, specifically the ending pool scene in TGG and the Reichenbach falls in TAB.
As explained here in further detail, John initially wrote the stories of series 4 as a 2-act structure. Unlike previous second episodes in the series, TLD actually brings the character arcs and resolves loose plot threads... except for those related to Eurus. When John was shot at the end of TLD, he had to go back and quickly revise the first two stories, using previously established charcters and plot points, including the girl on the bus, Faith Smith, and the water motif, and insert a very loose serialized thread that could be used to explain the presence of a third episode. This resulted in the creation of Eurus Holmes and TFP.
Eurus says to Sherlock as projections of water flood the screen:
Deep water, Sherlock, all your life, in all your dreams. Deep waters.
Series 4 and TFP in particular are a culmination of false climaxes; in order to make the story of TFP feel real, John connects it to plot points and thematic beats that don't make any sense.
Sherlock's powers of deduction have gone from being able to sense from a few scratches on a table made by a missing bust of Margaret Thatcher that the otherwise unrelated case is somehow connected to the looming mystery of Moriarty's return, then it turned into the missing A.G.R.A. stick and Mary mystery based on future information he couldn't have possibly had, and now it's evolved into not just a borderline-omniscient sense of all human activity and information, but a kind of manifest return, an inward destiny inevitably pulling him back to the waters that created him.
This is far cry from TGG or TAB where Sherlock can't remember how the earth rotates around the sun because there isn't enough room in his head.
TST is an incredibly bold departure from everything we've come to associate with the rest of the show. Series 4 as a text and its ambitions are only possible because of the way the rest of the show sets up these concepts. If series 1-3 set the stage TAB builds the narrative architecture, then series 4 draws the curtain.
In series 4, John writes Sherlock's brain like it's the collective well of all human knowledge. Essentially, similar to Eurus, he basically has psychic powers, and John takes the unexpected opportunity he's given to try to give Sherlock an origin story that explains their relationship, but in the end it's whatever the plot needs to work at any given moment.
The "deep waters" do exist for Sherlock, but not as an obstacle to return to that has nothing to do with John, but as something they can only face together. The entire reason why Sherlock even had the dream is because he was too focused on the obliquity of the ecliptic, or mulling over his relationship with John, to the detriment of telling him the truth, trapping them both in this cycle.
















