The Luftian Prophecy

Funny thing about prophecies. First, someone needs to be within hearing range to listen to the words which are being said. then, The words need to be understood; I'm talking language, understanding, an' all of that. Then, the prophecy has to reach the person it's being made about, so, to answer your question - sure I believe in prophecies, I just think they're useless.
A random citizen on the streets of the capital when asked about the Luftian Prophecy.

Summary

The basic outline of the myth is that, for want of a nail, the entire Surait Empire was lost.
A long time ago, in a land not so very far away, there was a grand lighthouse. This was no ordinary light house either - this was a lighthouse made of magic. The walls were of shimmering stardust and could hold against any giant's fist. The windows were fashioned with blessed water, so any light shinning through would be more powerful against the darkness. And the people of the empire were happy that they were defended.
One day, right before night bloomed, a solider found a nail missing from one of the doors on the top most floor. He sent a shout down to the next solider, and them onto the next, onto the next, etc., until finally a nail was fetched and sent back up the line. When one of the soldiers went to pass on the nail, she realized that the next person wasn't another solider as it should have been, but a snarling vampire with blood running down its chin.
She survived, and her account was written down, but for the rest of her life she was bitter about her failure to save the people she cared about the most.
About fifty years later, a message from the Luftian Lands reached the remains of the empire that "want" of a nail would lead to the end of the empire. Translated by the scholars of the time period (and also looking back at what had happened), it was determined that the perceived "need" for a nail was what brought down the lighthouse and allowed the forces of the night to rise and take over the Empire's lands.
This myth (coupled with the very real destruction of the Empire), is usually the first argument beings make when talking about the fallacies of prophecies.

Historical Basis

The Surait Empire was a long-reigning empire that stretched from one sea to the other, and they held tightly to the canals access. Early on in their history, when they were conquering the other nations nearby, they used many types of night beings as stepping stones toward their battle success. 
This entailed enslaving people and beings they thought were beneath them, and towards the fall of the empire they were battling night forces almost every day. These forces were family members who were looking to free kin, friends of those who had been taken, and even some sympathizers to the cause. 
Recorded history shows that the lighthouse was attacked first, and after the windows had been shattered, all the soldiers inside either dead or injured enough that they would be in the next battle, the amassed army swept across the nation, pillaging and burning. 
As for the "prophecy" of this all happening, it's been thought that the first shout detailing a weakness in the defenses (and that information being repeated), led some of the attackers to be in the right place at the right time.

Spread

This myth has spread widely and it is common knowledge. However, not everyone reads it in the same way.

Variations & Mutation

The original myth has changed several times over the course of the centuries. 

• The soldier's details (before the records were found), changed gender, nationality, death, etc.
• The item needed changes from a nail to a hammer (the nail was needed but couldn't be drive in)
• Others say that the "nail" needed was for the horseshoe of the messenger who was late

Cultural Reception

Different cultures and ethnicities see the tale as telling a different lesson. Some see it as destiny not allowing us to change large courses (no matter what we try to do to change the course of life's actions, some things don't change). Others see that there is a chance to change destiny, but that requires luck to be in the right place at the right time (they point out that if the messenger hadn't been late, this catastrophe could have been avoided). Others use this as a way to teach that small actions can have big consequences.  
Nothing really changes about the story and the identity of the empire in it since that's a well known common event.

In Literature

There are several books about the fall of the Surait Empire, and even some historical romances about lovers on different sides, or of one lover entering the battle to recuse their partner.  
Precisely because this is a well-known tale, there are many ways a person learns about it. There are children's books that use it for morals, there are scholar's works talking about how the fall of the empire impacted the entire world, and there are other books that only use the setting. There is an epic poem that was written from the "Darkness" point of view, penned by a vampire who had lost their entire clan to the Empire.

In Art

There are too many paintings about the fall of the Surait Empire, but the most famous (either by topic or artist) are listed below:

• The Battle of the Light House (no beings are depicted in this painting, it's how the area might have looked when the troops had moved onto the next location). The windows are shattered with glass sprinkled on the muddy ground, reflecting fires. 
• At Dusk (painted as an opposite to The Battle of the Light House). This shows all the troops poised to attack, and there's a slit in the door, larger than the average nail size, where a wide green eye is watching. 
• The Death That Stalks has the light house in the background, lighting striking it, and all around are ruins in which obviously dead bodies are lying (all the injuries depicted were gory and brutal - it was said that the painter lost their family to the Empire's enslavement).
• Nails is a modern look at the historical event and what "nail" might have meant. The collage holds a messager leading a limping horse, a weary solider holding a new nail to pass upwards in line, and a werewolf's lycan nails piercing a human skull.  

Date of First Recording

1216