- "That is the Mask of Truth, isn't it? You have a frightful mask. But being able to see into people's hearts and minds seems useful..."
- — Happy Mask Salesman
The Mask of Truth (まことのお面, Makoto no Omen?) is a recurring mask in the Legend of Zelda series. This mysterious mask, passed down by the Sheikah, allows the wearer to read the minds of Gossip Stones. The mask is shaped like the emblem of the Sheikah; namely, the eye with a tear. The retrieval of this mask is not mandatory in order to complete either game.
The Mask of Truth is given to Link by the Happy Mask Salesman in the Happy Mask Shop, after Link has sold the Keaton Mask, Skull Mask, Spooky Mask, and Bunny Hood, thus completing the Happy Mask side quest. If Link wears this mask in the Forest Stage he will be given a Deku Nut capacity upgrade. However due to a glitch in the game's system, once Link obtains the Poacher's Saw he cannot obtain the Deku Nut capacity upgrade. If Link wears the Mask of Truth while approaching the stage after obtaining the Poacher's Saw, the Deku Scrubs will either attack or give him Rupees. This has been fixed in Ocarina of Time 3D, the Nintendo 3DS re-release. If Link talks to Saria in the Sacred Forest Meadow while wearing the mask, she will point out that it makes her feel sad.
A man entered the Swamp Spider House with his dog. There, he found an unidentified male that gave him the Mask of Truth and a promise that, if he followed the instructions in the mask, he could become rich. Greedy, the man put the mask on and became cursed, being turned into a Skulltula-like creature similar to the other Gold Skulltulas found deeper within the building. When Link enters the Swamp Spider House, the cursed man begs him to defeat all the Gold Skulltula within and collect their spirits. When Link is successful, the curse is broken and the man gives Link the Mask of Truth.
In addition to allowing the wearer to hear Gossip Stones, it allows them to read the thoughts of animals when they are picked up and held above one's head. This can be used in order to ascertain the upcoming winner of the Doggy Race, allowing Link to acquire a Piece of Heart and amass many Rupees. If Link picks up the dog in Clock Town while wearing this Mask it will say something about getting all riled up when he sees "that Deku Scrub".
The Mask of Truth appears as one of the Item Cards on the Majora's Mask DLC Adventure Mode Map. When its item card is used on a map square it increases the player's defense for a single battle on said square. It is also an unlockable mask costume for Impa, fitting with its Sheikah origins.
The Mask of Truth never turns its wearer into a monster by itself.
The man wears the mask because of greed. This is shown by both the story as to how he turned into a monster and, when Link picks up the dog in the same room as the man while wearing the Mask of Truth, he is told that his master wore the mask due to his greed. Clearly, when the man put the mask on, he was performing an act of greed.
In Hyrule, specifically Ocarina of Time, Link sees an entire family that is cursed due to its greed. The physical manifestation of the curse involved spiders dispersed throughout Hyrule and the family being turned into spiders. This curse being born from greed is shown to exist.
The location itself was known for spiders in the first place. Outside, Link can read a sign stating, "Fearful Spider House," clearly referring to the cave behind it. Given the fact that the dog is in good health and not dead due to starving, the cave was obviously referred to as the Fearful Spider House before the man went there. This place is tied to the curse, and it was not simply the place chosen for the Gold Skulltulas to roam free due to its close proximity to where the man put on the mask. Instead, it was simply "activated", for lack of a better term. The switch is performing an act of greed in or near it.