Hola! Aloha! Gudentag! Whatever!
Now here's a special theory that may change your outlook on the widely accepted Zelda symbol. The triforce was long known to be a 3 (or 2) piece triangle representing many things... Din, Nayru, Farore, red, blue, green, power, wisdom, courage. But WHAT IF OUR ENTIRE LIFE WAS ALL A LIE!? Well I mean our entire lives were lies back when Zelda 2 came out... but only one game had been made at the time so wasn't a big deal, but we've had countless games since and what if there was still more to know? So here, we have the amazing, astounding, inexplicable... oh wait that word doesn't fit... WHATEVER here's a fourth triforce!

Now quick disclaimer, the theory I have is my take on it, as there's many crossroads where this theory splits. Also it conveniently fits in with Majoras Mask, man I love that game... Also the theory is officially called the tetraforce, but I just call it the forth triforce. Seriously, did we call it the BIFORCE when there were two pieces in the original Zelda? Does the fourth piece make a square? Well let's begin with the many, many, many paths this takes us.

Back in Ocarina of Time the hylian shield had 3 symbols, the triforce on the top, symbol of Hylia in the middle, and a... fourth upsidedown triangle??? Wait... there's always been a gap in the center of the tri... OMG! This design struck a flame in many's hearts. Could there be a fourth triforce out there??? Well this led to much investigation in every game in the series, with many interesting opinions. If no one knows about a fourth triforce that probably exists it has to be hidden somewhere. At the time people thought it could be in the dark world from Link to the Past, but Link Between Worlds kinda messes things up with how drastically different the dark world is, or, pfffft, Lorule... Current day candidates are Termina, the spirit realm, twilight realm, that world in Phantom Hourglass whatever it was called again, and any other parallel world in Zelda lore. Now if the fourth triforce isn't in another world, it may be hidden in Hyrule somewhere, but hold on. If each triforce was made by a goddess, which goddess made part 4?

Well here's where things get on my terms. In Majoras Mask a goddess of time is referred to quite significantly. Maybe this is the fourth goddess? Well the only other known goddess is Hylia, but she's incarnated into Zelda and she already owns the triforce of wisdom, so it has to be the only other goddess we hear of in the series. But of course, people like taking stretches, and they believe a sand goddess hinted in Ocarina of Time, birthplace of the speculation, made the triforce. And they back it up with another thing, if this triforce was hidden away and forgotten, does that make it evil? Back to the shield, while the 3 main triforces are up high, the fourth is down at the bottom, likely inferring it has fallen away from the light and became evil and dark. Only problem, the triforce of power is usually with Ganondorf, who isn't exactly the best example of good. But if this triforce WAS evil, the sand goddess, who may have made the race of thieves, the gerudo, could represent this unruly influence of the fourthforce. But yeah, that's all we got to support the idea of the statue of the spirit temple being a goddess and owning a trifourth.

Now that we got our goddess of time or some other unknown source making the triforce, what is symbolic to it? Well we can all assume this, the fourth piece likes purple. In Minish Cap there are 4 stones, the green stone of courage, the red stone of power, blue stone of wisdom, and purple stone of magic. Well that's definitely out of place, and so is the fact that the four sword creates 4 links in green, blue, red, and purple. Why the purple??? So with the significantly over mentioned time importance and fact that purple is involved and is also associated with magic, fans think this purple triforce is connected to time or magic.

Finally, does someone own the fourth triforce? Ideal hosts for the triforce include...

1.Vaati: very purple, likes magic, same games that have a fourth purple figure, and he's an evil traitor.

2.Ghirahim: CAUSE HE'S GHIRAHIM WHY NOT

3.Impa: probably the most likely candidate in my opinion, being reincarnated in many games as well and being the shadow sage. The shadow emblem shows three circles forming a triangle, and in the center an upsidedown triangle. And it's purple!

Do I think someone has the triforce piece yet? No. Maybe if it is discovered Impa will inherit it, but for now no.

Now with all that info out of the way, this IS a Majoras Mask theory right? Here's my final input. Now the triforce has been said to be magic or time orientated, but I got something better than that for you. In each of Termina's 4 worlds there is a great fairy. In the swamp, fairy of courage, mountain, fairy of power, ocean, fairy of wisdom. But in the canyon, there's the fairy of KINDNESS. In my opinion this fits much better with the theme of the triforce. You can be courageous, intelligent, powerful, or even... magical? Timely? Well yeah, but you can also be kind. Now an ideal hero would be courageous, smart, and tough. But it would be even better if he were kind. Not really much heroism if you're a jerk eh? And kindness fits in as a theme of MM too, as you help many people on your journey. If Termina is a mirror world of Hyrule, there could be this kindness factor in Hyrule too...

Now this isn't the end yet, I'll mention the 4 triforce theory again later, but for now I'm done here. Next time, well, I'll do what I said THIS theory would be... yeaaaaaah... later!

Mecha Leo :

I was at one point in time going to write my own fanfiction where the Goddess of time was Hylia's Termanian counterpart, who gaurded the Triforce's Termanian counterpart, the Triforce of Time.

But Kindness is another interesting contender.

I would like to add something.

Kindness, can be shown both by good, and evil people. ie, look at Count Dooku, from Star Wars, He seemed like a very fair person to me, and not one to kill his own guys let alone mistreat them. (though the Clone Wars series completely ruined this notion, and made him into some sort of generic sith. . . )

Many people can be kind to their allies, and treat them well, while it is generally recognized as a good quality, it can be used for evil.

Also notice that the last piece is upside down.

Placing this piece in the center would lead to a perfect peice of triforce, perphaps making one invincible.


One time, me and bombchu sat down, and theorized about the power of the Triforce.

We were trying to figure out just what good courage was exactly, and then it came to us.

Each piece's power is this.


1 Power

Increases it's user's amount of power in any area that they wish. It is not limitless, but it does come in very handy. It can come in the form of being able to perform stronger spells, or more of a stronger spell before one is exhausted.

2 Wisdom

Wisdom does not grant one more information, but rather allows one to use better the information that one already has. One could learn incredibly quickly with this in their possession, and think with speed. The more knowledge that one would obtain, the more powerful this triforce piece becomes.

3 Courage

Courage allows one to put all emotions conflicting with what the mind realizes must be done aside and strengthens determination and anger. With this amazing ability to focus, and the ability to ignore all inner conflict, the power one posses is maximized. This triforce piece is absolutely necessary if you want the full power of the triforce, but the ability to put emotions aside could make you. . .

a monster.


Isn't that an interesting concept?

But what about . . .


4 Kindness?

Like Wisdom brings Power to balance, I see Kindness bringing Courage to it's balance.

I believe that this very well could be the fourth Triforce Piece, that would add completion.

Sword legion : Well like I said, there's more on the topic I'd like to talk about to help support the idea of obtaining a whole triforce and gaining powers far beyond a singe wish, but it would be for another thread.

Mecha Leo : this is an incredibly interesting idea for a 4th triforce piece but I would like to point attention to something it might be another candidate for the 4th triforce SERVITUDE. In hyrule warriors the sacred temple stage where you get the master sword you need to unlock 3 statues 

1. Fire and water- opened by darunia and ruto
 
2. Twilight- opened by midna

3. SERVITUDE opened by impa


like you said impa does reincarnate in the games frequently so perhaps that would be the case 
again I want to say how detailed this theory is and how much I enjoy also I hope you don't mind I tell this theory to some of my friends