Sage

The Sages are a part of the The Legend of Zelda series introduced in A Link to the Past. They always operate as a group and appear to have the overall responsibilities of protecting Hyrule and as such, aid the Hero on his quest. Oftentimes, Link is required to save them or awaken them as (the new) Sages first. This usually is because the villain attacking Hyrule is aware of their powers, and as such, they tend to take care of the Sages quickly.

Many things about the Sages still are a mystery, and instead of answering questions, the younger games have made things even less clear. A Link to the Past introduced the Sages, back then known as the Wise Men and the Maidens. The Maidens were a group of seven girls, each descending of one of the ancient seven Wise Men. This system of a group of seven Sages was carried on in Ocarina of Time and Four Swords Adventures. However, in The Wind Waker, a second group was introduced. This group is responsible for keeping the Master Sword capable of defeating evil. It is unknown how this group relates to the first group and with how many they are. Twilight Princess complicated things further by seemingly featuring the first group of Sages. However, their nature was very different from that of the other incarnations of the Seven Sages. For one, they were ghost-like creatures, all looking the same, while all other Sages have been shown to be random people who just happened to be chosen as the next "Sage of (...)". Secondly, they seemed to be with only six, Princess Zelda not being part of their group, even though they were her tutors.

A Link to the Past
In A Link to the Past, the prologue mentions the Seven Wise Men (renamed "Sages" in the GBA re-release ) as the ones who, with the aid of the Knights of Hyrule, sealed Ganon away in the Sacred Realm long ago. During the beginning of the game, it is made clear that Agahnim, the King's righthand, is using his power to find and capture the Seven Maidens, who are the descendants of the Seven Wise Men and have inherited their status of Sage. Agahnim planned to send them to the Dark World one by one in order to destroy the seal that kept Ganon locked up.

Princess Zelda was going to be the seventh sacrifice, but she managed to telepathically send a message to Link, requesting him to rescue her. Link did succeed, but Princess Zelda was recaptured later, while Link was gone in order to obtain the Master Sword. Link then traveled to the Dark World to save each of the Maidens. After all the Maidens are released, they destroy the barrier around Ganon's Tower, allowing Link to defeat Agahnim, and then subsequently, Ganon.

Ocarina of Time
In Ocarina of Time, the purpose of the Sages is further explored . Each Sage has their own temple somewhere in Hyrule and corresponds to a certain element. The elements presented in Ocarina of Time are:

Rauru
Rauru is an ancient Hylian and the Sage of Light in Ocarina of Time. He is one of the ancient Sages, and possibly the only remaining one. Rauru makes his appearance after Link opens the Door of Time and draws the Master Sword from the Pedestal of Time. Rauru recognized Link as the destined hero and therefore kept him sealed within the safety of the Sacred Realm for seven years.

Saria
Saria is the Sage of the Forest When Link went to the Sacred Meadow Grove, he discovered that Saria's "secret place" housed the entrance to the Forest Temple. Link went in and, after a lot of exploring and fighting, managed to defeat the temple's evil spirit, Phantom Ganon. By doing this, he allowed the new Sage to awaken.

Darunia
Darunia is a Goron introduced in Ocarina of Time. He is the leader of the Hyrulean Gorons and the Sworn Brother of the King of Hyrule. Despite his stern appearance, he loves music and dance and cares deeply about his people. His known relatives are a distant ancestor who became a legendary hero by defeating Volvagia, and his son Link who was born sometime in the seven year absence of the Hero of Time. Darunia eventually becomes the new Sage of Fire when Link cleanses the Fire Temple.

Princess Ruto
Princess Ruto is a Zora introduced in Ocarina of Time. She's the daughter of King Zora, the king of the Hyrulean Sea Zoras, and attendant of Lord Jabu-Jabu, their patron deity. Her mother is suggested to have passed away some time ago. She's an only child, and described as wild, tomboyish and selfish. This does not mean that she neglects her responsibilities though. Ruto becomes the new Sage of Water after Link destroys Morpha.

Impa
Impa is a character seen frequently throughout the The Legend of Zelda series. Typically, Impa is an older woman who serves the Royal Family of Hyrule. She always appears to know much about the legends and secrets entrusted to the Royal Family. Impa also serves as a nursemaid and/or bodyguard to Princess Zelda and often offers guidance to Link. While she was part of the story of the very first game and of its sequel, she did not appear within the canonical games until Ocarina of Time. She awoke as the Sage of Shadow.

Nabooru
Spirit (Nabooru), Nabooru is a Gerudo introduced in Ocarina of Time. She is the second-in-command of the Gerudo, Ganondorf being her only superior. She has a second-in-command herself who is without name. Nabooru is higly respected by the other Gerudo, who are unaware of her rebellion against Ganondorf. During the events of Ocarina of Time she becomes the new Sage of Spirit and aids Link in his battle against Ganon.

It was revealed that the original Sages built the Temple of Time to protect the Triforce against those who would use it for evil.

After seizing the Triforce and becoming the ruler of Hyrule, Ganondorf caused the temples of the Sages to become infested with all kinds of monsters, so that the Sages-to-be would not be able to fullfill their duty and aid Link. However, Link managed to get rid of them and help each Sage to gain their power. Eventually, Link fought Ganon in a one-on-one battle and managed to beat him with the Master Sword. When that happened, the Sages joined their powers and sealed the King of Evil into the Sacred Realm. As such, it is suggested that these are the Sages referred to in A Link to the Past.

The Wind Waker
The Wind Waker introduced a new group of Sages. These Sages are responsible for keeping the Master Sword capable of defeating evil. It was not stated how big this second group was, but it at least consists of two Sages: the Sage of Wind and the Sage of Earth.

These songs empower the Master Sword and serve to awaken the new sages.
 * The Sage of Wind prays in the Wind Temple on Gale Isle, using the violin to play the Wind God's Aria.
 * The Sage of Earth prays in the Earth Temple on Headstone Island using the harp to play Earth God's Lyric

Before he was sealed away by the Great Flood, Ganon had ensured his victory by killing off these two Sages (Fado and Laruto). In order to stand a chance against him, Link had to find the new Sages (Makar and Medli), awaken them and safely guide them to their respective temples. After Link defeated Ganon, he and Tetra were picked up by Tetra's crew who apparently had also already picked up Makar and Medli.

The Wind Waker also confirmed the original six sages from Ocarina of Time, displaying their likenesses in stained-glass windows in the submerged Hyrule Castle basement where the Master Sword was kept.

Four Swords Adventures
On a stormy night, Princess Zelda and the shrine maidens fear that the reason for these events is that Vaati's seal is weakening. They summon Link and bring him to the castle so he can protect them while they open the portal to the Four Sword Sanctuary. When they do however, a shadowy figure appears from the portal. This figure was Dark Link, who then kidnapped the shrine maidens and sealed them in crystals. Link must then go around Hyrule and free the maidens from Vaati's wrath.

Blue Maiden
The Blue Maiden the first of the Six Shrine Maidens from Four Swords Adventures. In the game your objective is to rescue her, along with the other five Maidens, and Zelda, from Vaati's Dark Shield. The Blue Maiden is found in the Whereabouts of the Wind, specifically in Hyrule Castle after you rescue her from the clutches of Phantom Ganon. What makes this Maiden unique from the rest of the other Maidens, is that she has a small village named after her.

Yellow Maiden
The Yellow Maiden is the second of the Six Shrine Maidens from Four Swords Adventures. In the game your objective is to rescue her, along with the other five Maidens, and Zelda, from Vaati's Dark Shield. The Yellow Maiden is found in Eastern Hyrule, specifically in the Eastern Temple after you rescue her from the clutches of Stone Arrghus.

Green Maiden
The Green Maiden is the third of the Six Shrine Maidens from Four Swords Adventures. In the game your objective is to rescue her, along with the other five Maidens, and Zelda, from Vaati's Dark Shield. The Green Maiden is found in Death Mountain, specifically in the Tower of Flames after you rescue her from the clutches of several Dodongos.

White Maiden
The White Maiden is the fourth of the Six Shrine Maidens from Four Swords Adventures. In the game your objective is to rescue her, along with the other five Maidens, and Zelda, from Vaati's Dark Shield. The White Maiden is found Near the Fields, specifically during Infiltration of Hyrule Castle after you rescue her from the clutches of Jalhalla.

Red Maiden
The Red Maiden is the fifth of the Six Shrine Maidens from Four Swords Adventures. In the game your objective is to rescue her, along with the other five Maidens, and Zelda, from Vaati's Dark Shield. The Red Maiden is found in The Dark World, specifically in the Temple of Darkness after you rescue her from the revenge of Phantom Ganon.

Purple Maiden
The Purple Maiden is the last of the Six Shrine Maidens from Four Swords Adventures. In the game your objective is to rescue her, along with the other five Maidens, and Zelda, from Vaati's Dark Shield. The Purple Maiden is found Desert of Doubt, specifically in The Pyramid after you rescue her from the clutches of a Big Moldorm.

Twilight Princess
In Twilight Princess, the Sages (excluding Princess Zelda this time) appear as ethereal forms of old men. However when one of the Sages turns his head, you can clearly see that they are wearing masks and that they do not have faces underneath, indicating that they are unable to be seen without their robes. They are shown using the Sword of the Sages in a failed attempt to execute Ganondorf, which resulted in the death of the Sage of Water and the banishment of Ganon to the Twilight Realm.

Due to the appearance of the Sages' insignias on their robes, it is possible these ethereal Sages are the spiritual incarnations of the powers of the six Sages awakened in Ocarina of Time, or in other words, the unawakened forms of the six Sages that were awakened in the future era. This would mean that while Saria, Darunia, Ruto, Impa, Nabooru and Rauru were the pre-destined physical counterparts, the source of their powers came from these spirit Sages. This would explain why the six Sages appeared as normal beings in the past era of Ocarina of Time but gained great power later in the future era after the Hero of Time helped each of them to fuse with his or her own respective ethereal Sage (the ones shown in Twilight Princess). This would mean that these ethereal Sages, alongside the Oocca, were the original builders of the Temple of Time, as Rauru stated in Ocarina of Time, and, by extension, the creators of the Master Sword itself.

Phantom Hourglass
In Phantom Hourglass, there is a graveyard on the Isle of Ruins where nine sages were laid to rest. In order to traverse Brant's Tomb, Link would first need to find a way into the graveyard. The graveyard contains a set of directions on six of the sages' gravestones. The other three Sage's tombstones are unreadable.

"...Those without the way of the six sages are doomed."

- Stone tablet inside Brant's Tomb.

If these directions are not followed, Link will wander helplessly through Brant's Tomb, much like in the Wind Fish's Egg or the Lost Woods.

Trivia

 * Although the American version of the game confirms that the sages were Zelda's tutors, the Japanese version of The Legend of Zelda: Twilight Princess says that Auru tutored her instead.