Mt. Aleph, a dormant volcano situated in northwestern Angara, is the site of Sol Sanctum. The mountain holds many mysteries and great secrets, and the truth about its origin remains unexplained. At its foot is the town of Vale, whose residents revere the mountain and the sanctum as sacred without being aware of the full extent of the sanctum within. It contains the Elemental Star Chamber, the resting place for the four jewels named the Elemental Stars; the mountain and the stars it contain are the focal point of the system that, along with the four Elemental Lighthouses the Stars activate, would return the powerful but dangerous force of Alchemy to the world. It is effectively the most important location in all of the Golden Sun series.
This mountain houses Sol Sanctum and the Golden Sun forms at its peak. The Mt. Aleph Boulder, which crashed through Vale and supposedly killed Felix, his parents, and Kyle, came from this mountain as well. Mt. Aleph also houses the secret Elemental Star Room, which keeps the four Elemental Stars necessary to light the four lighthouse beacons.
Background and Story
The origins of Mt. Aleph are indecipherable, let alone those of the structure inside it, Sol Sanctum, though presumably it has been around since the world's ancient past, the period when global war was fueled by the fantastic power of Alchemy. When Alchemy was sealed away from the abusive tendencies of mankind, the process involved putting out the elemental beacons alight atop each of the four Elemental Lighthouses situated throughout the world - these beacons are the purified essences of each of the four elements that comprise all matter. These essences ended up contained within the four jewels named the Elemental Stars, and these in turn were hidden away within the deepest chamber in Mt. Aleph. However, while the chambers within Mt. Aleph are designed to keep out those who are not Adepts, they ultimately allow those who are Adepts to take the Stars, cast them into their respective Lighthouses, relight their beacons, and return the power of Alchemy to the world.
A town that emerged at the foot of Mt. Aleph, Vale, developed a cultural reverence for the mountain due to the influence exuded by the Psynergy stones within it granting them varying degrees of Psynergy abilities as Adepts. Their legends believe that Mt. Aleph, whose name supposedly refers to "the origin of all things", is the greatest source of Alchemy, and that Alchemy is the foundation of Psynergy (whether this is fully accurate is unknown). To the people of Vale, Mt. Aleph keeps watch over Vale, and therefore daily meditation is on order to help keep them safe. Most relevant of all, they believe that Vale stays pristine because of "Mt. Aleph's purity", and that if that purity is tainted, "terrible retribution" is risked; while they do not know of the chambers beyond the first ones they see, this is in some ways true, for the chambers deep within Mt. Aleph are also designed with a dangerous trap that would spell doom for those who do not solve the riddle leading into the Star Chamber the proper way.
Three years before Golden Sun, a raiding party of Mars Adepts from the far north led by Saturos and Menardi come to Mt. Aleph and infiltrate it in an attempt to take the Elemental Stars for themselves. However, they fall victim to the trap when they attempt to gain access to the Elemental Star Chamber, and all of the Mars Adepts perish while Saturos and Menardi barely escape Mt. Aleph with their lives. The trap causes a magically-generated thunderstorm to surround Mt. Aleph (and only Mt. Aleph and the immediate area around it); this causes a massive boulder situated somewhere on the mountain, which the Valeans refer to as the Mt. Aleph Boulder, to start rolling down and fall, plowing through Vale below.
Three years later, the elderly scholar Kraden takes a group of young Adepts with him - Isaac, Garet, and Jenna - into an unauthorized investigation of Mt. Aleph's sanctum, which he claims is an important venture for the sake of their education as Adepts. (In actuality, Kraden wants to discover the secrets of Alchemy because he was ordered to by his effective master, Babi, the lord of Tolbi.) Secretly following them into Mt. Aleph, however, are Saturos and Menardi, who have returned to attempt another raid of Sol Sanctum for its Stars, this time bringing two companions in Felix and Alex. When Kraden's group manages to solve the riddle and find the Elemental Star Chamber without triggering the trap from three years earlier, Saturos' group makes an entrance and forces them to retrieve the Elemental Stars for them. Saturos acquires the Stars of Mercury, Venus, and Jupiter.
However, when Isaac removes the fourth star, the Mars Star, from its pedestal, Mt. Aleph suddenly begins to erupt as a volcano, for the four stars had been set upon the pedestals in a way that their powers originally kept the flowing magma underneath subdued. Saturos' group is forced to leave the Mars Star behind with Isaac and Garet, while taking Jenna and Kraden with them as their captives; they know that if Isaac and Garet survive, they will attempt to pursue Saturos to retrieve Jenna, and will bring the Mars Star with them. After Saturos' group flees Mt. Aleph, Isaac and Garet come face-to-eye with the monolithic entity that has slumbered within Mt. Aleph until this moment, the Wise One. The guardian of Alchemy's seal, the Wise One commands the boys, should they choose to accept, to pursue Saturos' group and prevent them from using the Elemental Stars to light the Elemental Lighthouses, states that should Alchemy be returned to the peoples of the world, it would only mean disaster when it is inevitably abused. The Wise One teleports Isaac and Garet to safety so they can return to Vale, and uses his near-godlike power to redirect the volcano's lava flow away from Vale and save it from destruction.
The eruption of Mt. Aleph immediately begins to have a profound effect on the entirety of the world of Weyard; the mass of Psynergy stones that long laid hidden within the mountain are spat out and showered all over the world in small chunks. The stones draw out the Psynergy abilities previously dormant in people throughout the world that come into direct contact with the falling stones, causing them to become new Adepts. Wild animals unable to mentally handle the influence the stones exude are driven feral, making the world as a whole a much more dangerous place. Most spectacularly, the plain at the eastern end of Angara, Mogall Prairie, very quickly transforms into a forest filled with hostile monsters. Despite all this, Vale itself is unaffected by the eruption, save for periodic tremors and a brief heating of the river that runs through town.
From here on out, the events of Golden Sun and The Lost Age take place, the eruption of Mt. Aleph having served as the primary event to set up for the majority of the main storyline. Isaac and Garet lead a party in pursuit of Saturos' group as per the command of the Wise One, and they are ultimately able to slay Saturos and Menardi in combat, but by then the Elemental Lighthouses of Mercury and Venus have already been lit, and Felix continues Saturos' quest with the remnants of his group. Much later, Felix's group discovers proof of a shocking fact about Alchemy; for all its potential danger, its presence is the effective sustenance of the physical world of Weyard, and the world has been physically shrinking and breaking apart over the ages as a direct result of its absence. When Felix and Isaac's parties meet in a dramatic series of events upon Jupiter Lighthouse, whereupon it is activated with the Jupiter Star, Felix is able to explain to Isaac in full why breaking the seal on Alchemy is necessary to prevent the world from a gradual, yet premature end, and Isaac agrees to join forces with Felix on the rest of the latter's quest.
However, even as Isaac and Felix's combined party moves to light the final lighthouse, they are unaware that they have all been used: Alex, who had long since went off on his own after helping Saturos' party light the Lighthouses, desires the full powers of Alchemy for himself all along. Alex returns to Mt. Aleph and begins climbing up its exterior to its peak, knowing that standing there when the last lighthouse is lit will grant him the benefits of absorbing pure alchemy made real, at the heart of its power. The Wise One, fully aware of this and everything else, confronts the Adepts at the aerie of Mars Lighthouse over their decision to break the seal on Alchemy and free a power that would inevitably lead to wars and strife, and notifies them of Alex's plot; soon, he puts them through a dramatic and harrowing test for the right to light Mars.
Ultimately, Mars Lighthouse is lit, and the automated process shared between the Lighthouses and Mt. Aleph to bring back Alchemy to the world begins in earnest. The four Elemental Beacons atop each lighthouse shoot out beams of energy in tandem, and the beams gather into the airspace immediately above Mt. Aleph; the golden ray of energy that forms as a result of the four beams merging is what is referred to as the Golden Sun - pure Alchemy made real, at the heart of its power - and proceeds to bathe Mt. Aleph's peak, as though the physical mountain itself is infused with the power of Alchemy. At the end of the process, Mt. Aleph glows a radiant gold, and Alex, having stood in the center of the Golden Sun's ray as the energy passed through his body, gains great power and nearly limitless life. Ecstatic over the success of his grand plan, Alex immediately attempts to summon a thunderstorm upon Vale and the foothills of Mt. Aleph to flex his newfound power... but is baffled to see nothing happening.
All of a sudden, the Wise One appears before Alex, who tells him that though he did gain bolstered power and life, he did not gain the fullest extent of the power of Alchemy from the Golden Sun as Alex had intended; back when the Wise One met Isaac and Garet in the Elemental Star chamber when Mt. Aleph was erupting, the Wise One predicted Alex's plan and and set in motion a measure to counter it by imbuing the Mars Star with a particular property, which as a result caused the Mars-aligned portion of the Golden Sun to enter Isaac's body on Mars Lighthouse instead of Alex's on Mt. Aleph. Therefore, Alex is not all powerful as he would have been otherwise. Believing the Wise One is trying to anger him, Alex attacks him with the power he has, but the Wise One telekinetically drives him into the ground and leaves him subdued.
Mt. Aleph and the surrounding landscape begin to quake and change form, and the mountain itself starts sinking into the ground; since Alex is unable to move, the Wise One explains that he may not survive the changing of the earth and the heavens because he will be "swallowed by the earth", but ends by noting that if Alex does survive, they might meet again in the future. Alex presumably meets his fate when the golden mountain half-submerges, leaving its top portion above ground as a permanent monument while everything in its vicinity is reduced to rocks and rubble. The town of Vale itself is destroyed; however, prior to the activation of the final beacon, the Wise One warned all the townspeople to evacuate, thus saving their lives.
The new, half-submerged gold-colored state of Mt. Aleph has been a subject of much debate on community forums since the release of Golden Sun: The Lost Age. It may in fact be the Stone of Sages talked about in-game (since it is said in-game that it's the light of the Golden Sun that "gives shape" to the Stone of Sages), meaning it would be the massive vessel that "dominates everything" for being what brings the power of Alchemy back to the peoples of the world. Mind Read dialogue in post-game Prox, normally inaccessible without a hacking device, suggests that a future conflict may revolve around people vying for control of the Stone of Sages.
In Dark Dawn
By the time Golden Sun: Dark Dawn begins, Mt. Aleph is an active volcano, and because of changes in the landscape caused by the Golden Sun event, it is now inaccessible by land. At some point, the villagers of Vale resettled at nearby communities, with Kalay being the largest known.
In the meantime, Isaac and Garet have been observing Mt. Aleph from their cabin located on the nearby Goma Plateau. They make plans to use the Soarwing, an invention of Ivan's that allows an Adept to fly using Psynergy, to one day travel to the volcano. However, their only Soarwing is broken by Garet's son, Tyrell, when the young Adept tries to use it without proper training. While most of the repairs are simple, they lack a crucial element, a Mountain Roc's feather. Thus, Isaac and Garet send Tyrell, along with Isaac's son, Matthew, and Ivan's daughter, Karis, on a quest to retrieve a feather so that the Soarwing can be repaired as soon as possible. It is suggested that the urgency of the situation is because Isaac wants to fly to Mt. Aleph as part of his investigation into the mysterious Psynergy Vortexes that have recently appeared.
The name Mt. Aleph is stated by the legends of the people of Vale to refer to the origin of all things. Among Mt. Aleph's allusions to real-world culture is that its name is based on the first letter of the Hebrew alphabet, א, which is called an Aleph. The Hebrew connection is likely intended to indicate a parallel that can be drawn between Mt. Aleph and the Biblical Mt. Sinai, where the Ten Commandments were handed down by God; in Golden Sun, for comparison, the god-like entity the Wise One gives his commandment to Isaac while they are still in Mt. Aleph, which would set Isaac off on his quest.
After the initial dungeon is completed, Mt. Aleph cannot be returned to, even with the use of a cheat device, and is used exclusively in cutscenes. In The Lost Age a well known trick can allow the play to walk "into" Mt. Aleph, but there is no special code for the area, and it behaves in the same manner that any ordinary part of the world map would.