The Voice of all things is probably the most mysterious ability in the world of One Piece. It has yet to be fully explained to us, and we have no idea where the ability came from or why it even exists. Every time we learn something new about the ability, we are left with even more questions.

Let’s take a look at Rayleigh when he first mentions Roger’s ability to hear the voice:

Up until recently, the only people in the series that were confirmed to be able to hear the voice were Roger and Luffy. At the time this ability was revealed, it was the rarest (non-devil fruit) ability in the One Piece world, even more rare than Conqueror’s haki. Yet, in this panel, Rayleigh mentions the ability without explaining it at all, as if the ability were well known throughout the One Piece world, or at least the grand line. Additionally, none of the straw hats saw fit to question him about it.

Some might view this as Oda simply withholding information from us, but this particular part of the Shabondy Arc was heavy with story reveals, we were even given some hints to the Void Century as well as Raftel itself. If Oda were going to explain this rare ability to us, wouldn’t this have been the appropriate time?

I believe that the reason that Rayleigh did not explain the ability is that there are many people on the grand line with the ability to hear the voice of all things. On top of this, we recently learned that there are different “types” of the ability. In chapter 821 we learned that not only are there those who can hear the voice, but those who can speak it as well:

I believe Momonosuke is a part of a special group of people that I will call “the Speakers of the Voice.” Momonosuke was able to command Zunisha to defend itself, something that Luffy, Roger, and Oden were not able to do.

Why wasn’t Luffy able to command Zunisha? Why wasn’t Roger able to command Zunisha? Most importantly, why wasn’t Oden, Momo’s father, able to command Zunisha either? The answer for now will remain unanswered to us, but what we CAN say is that there are those who can hear the voice, and those who can speak to it as well, and Momonosuke seems to be one of the Speakers of the Voice.

Speaking of Momonosuke, his relationship to the voice is incredibly strange. He was not able to “read” the Road Poneglyph like Roger was, but he was capable of commanding a 1,000 year old elephant to do his bidding. From this, we can gather that not only are there different types of the ability, but there are people who are only capable of hearing or speaking to certain voices. Momonosuke could hear the elephant, but could not “hear” the Poneglyph’s contents. Even Luffy himself can not yet “hear” the Poneglyph’s contents, but he was perfectly capable of hearing Zunisha’s cries as well as the Sea Kings at Fishman Island. Shirahoshi/Poseidon might also be a type of Speaker of the Voice, a bloodline that can command or even sentence Sea Kings. This tells us that just because you can hear or speak to the voice of one certain thing does not mean you can hear or speak to the voice of something else. While people like Luffy might not be able to speak to Zunisha, Luffy might be a kind of speaker that can speak to something else. But what exactly? Let’s put this thought on hold for now.

So far, we have learned of those who can hear the voice as well as those who can command certain things or beings through the voice. However, there is a third type of speaker, a powerful type of commander that can sentence. So far, we have seen one confirmed example of this:

Zo was sentenced to walk for all eternity. By whom? We’ll get back to that thought in a bit. For now, I want to talk Whitebeard and Kaido, whom I believe are the first examples of sentencing that we have seen in the series.

When we were first introduced to Kaido and his inability to die, many theories were created as to what his power might be. What keeps him from dying?

I remember reading people’s comments such as “he should just jump into the ocean” or “he should just eat more than one devil fruit.” And while at first I thought the fact that Kaido hadn’t tried either of these things was due more to plot convenience than anything else. But then another thought occurred to me: What if Kaido had already tried these things during his life?

Let’s talk about some things that we already know about Kaido that will be important to this theory:
1. Kaido murdered Moria’s entire crew as well as Momo’s parents
2. Kaido attempted to take on Whitebeard right before the Whitebeard war
3. Kaido has been given the death sentence repeatedly for his crimes

These points are important because they tell us that:
1. Kaido brazenly murders
2. Kaido had some reason to attack Whitebeard
3. Kaido has committed atrocities that many deem punishable by death

And now about Whitebeard:
1. According to Buggy, no one messes with the Whitebeard pirates for fear of angering Whitebeard
2. The other Yonko didn’t dare cross him, even in his old age and sickness
3. Whitebeard’s second division commander slot had been open for ages before Ace filled it

These points are important because they tell us that:
1. At some point, Whitebeard showed the world what happens to those who mess with the Whitebeard pirates
2. The Yonko wouldn’t cross Whitebeard due to more than just his reputation
3. Whitebeard had reservations about filling an empty slot in his crew, possibly due to pain of loss

And now, Kaido’s first words:

Many fans including me at first simply dismissed this statement as “Whitebeard did a good job by dying.” But many people in One Piece have died, why did Oda decide to have Kaido specifically chose to mention Whitebeard here?

Do you see where I’m going with this? I believe the story goes like this:

Kaido was a young, incredibly dangerous pirate who had dreams of claiming One Piece, and was making a reputation for himself at an alarming rate to the World Government. He made his name well known throughout the new world for his strength and brutality, through feats such as crushing and murdering Gekko Moria’s entire crew. At some point, Kaido became cocky and decided to make a move for the One Piece, but of course, he would have to go through the King of the Sea, Whitebeard. Kaido made his first move by crushing Whitebeard’s second division and killing the second division commander. Enraged, Whitebeard unleashed his full wrath on Kaido and defeated him. It was a brutal battle that left both Whitebeard and Kaido permanently scarred, and in a final act of revenge, Whitebeard used his abilities as a Speaker of the Voice to sentence Kaido to an undying existence, and then cast him into the sea. As Kaido possessed a devil fruit, he was doomed to drown helplessly for eternity, without dying. The world was shocked and awed by the true wrath of Whitebeard,who had just crushed the strong young pirate for murdering a member of his crew. Kaido drifted at the bottom of the sea for months or even years before he was finally brought back up to shore by some person or some sea king (for whatever reason lol). Back to the surface, Kaido was delusioned and angry by his months/years of suffering and was left with suicidal tendencies. The world was terrified by the man who they all thought had been killed by Whitebeard making a reappearance (possibly by sinking prison ships). When Kaido was convinced that he could not die, he began to amass his power in the form of eating multiple Zoan-type devil fruits and gaining their abilities, earning him the name of Hundred Beasts Kaido, the man with many Zoan forms. Kaido never forgave Whitebeard for the curse that he placed upon him, and for this reason continuously had fits of rage towards Whitebeard, even attempting to take Whitebeard’s life before Marineford. With Whitebeard dead, Kaido was left with his undying body, and his dreams of claiming One Piece once reaffirmed.

I believe this would explain Kaido’s suicidal tendencies, why he actually hasn’t died from eating multiple devil fruits/drowning, the pirates of the worlds’ acknowledgement of Whitebeard even in old age, the fact that the Yonko dared not cross him, and even why in his old, sickened state that Whitebeard was still viewed as the strongest pirate on the sea, as he was a Speaker of the Voice.

But where did this ability come from? What is its overall purpose in the story?

Before I get into the meat of this section, I want to talk for a brief moment about the geography of the One Piece world:

We all know the layout of the One Piece world, a grand line surrounded by two calm belts and four blues. We also know that the grand line is brutally difficult to navigate, and the weather and ocean patterns are far from natural. Keep this in mind. Now that that’s out of the way:

DISCLAIMER: This next section is fairly far fetched.

There is so little information on this “Sea Devil.” The only time we have ever heard of him was during Shanks’ conversation with Buggy at the beginning of the series. Therefore, it’s difficult to really say who he is or where he comes from. So for the sake of continuing onward, let’s just refer to the Sea Devil as a “god”, or more specifically, the creator of the world of One Piece.

I believe that this god created the One Piece world using his natural power as THE Speaker of the Voice of all Things. Whereas every other being in the future’s abilities at speaking the voice would be somewhat limited, the god was able to use the voice with no restrictions, and used it to create the entire One Piece world alongside “children” to worship him. The god, however, did not create water (this will be important for later).

The people were not completely submissive to his will at first, so 1,000 years ago, he displayed his frightening power by sentencing the strongest being in his creation, the first to deny him, to walk for all eternity (Zunisha). Witnessing this power, the people of the world were left to tremble before him. Over the next 100 years, the god grew satisfied with the people’s worship of him. Out of arrogance, the god even gave people his Fruits, which gave people one of his many powers.

There were those, however, who were not satisfied with living under the tyranny of the god, believing him to actually be a Devil, and realized that they could use his power themselves:

They formed a society that devoted themselves to finding their own purpose without the intervention of any god. They began to study reality and science in secret, and eventually formed an extremely advanced society of people who were able to speak the Voice. Using their scientific advancement, they created the oceans as places that the devil could not go as a way of challenging his power. They formed their kingdom on an island in the middle of the ocean, where the god could not reach them-the Ancient Kingdom. The founders of the Kingdom even gave themselves the initial D. as an act of mockery to the god, proclaiming him as a devil and identifying themselves as his “direct descendants” or “children of the Devil” as they were able to Speak with his Voice. (It’s important to note that the family of D. were not the only ones who could speak the voice, the other members of the kingdom could do so also)

The Great Kingdom went to war with the devil and his faithful children. The family of the D. were brutally outnumbered, but fortunately they were prepared. They created three ancient weapons to help them with the war. The rest of the world and even the Devil itself were so shocked by the sheer power of the ancient weapons that they didn’t notice what the Great Kingdom was actually working on: a way to kill the Devil: The project to kill him and to unite the world into was written down on the Rio Poneglyph. The One Piece, whatever it is, is somehow crucial to this plan. However, this plan was put on hold when the Kingdom began to succumb to the incredible power of its opponents.

The family of the D. used their trump card (which I will not reveal yet for theatrical purposes) to imprison the devil within the manmade ocean, where he was as helpless as those who ate his fruit. They imprisoned him somewhere in the ocean (earning him the nickname of Sea Devil), and sent the island of Raftel along with the One Piece and the Rio Poneglpyh to the bottom of the sea, then used their skill with the voice to permanently alter the geography of the One Piece world, making the rout to One Piece (and the devil itself) almost impossible to fully traverse. The members of the Great Kingdom who were not the family of D. used their abilities to create the Poneglyphs so that the world would never forget the terrifying power of the Sea Devil, and the struggle they went through to free themselves from his grasp.

However, as the war raged on for more decades, the Great Kingdom and its people were all but wiped out. The 20 kingdoms that had opposed them stood together and formed the World Government, as a way to ensure that chaos of that extent never ensued again. Eventually, those who were alive during the war had passed away. The government realized that with the Sea Devil imprisoned, their main priority should be to preserve peace and order at all cost. They had destroyed all documentation of the century and its history became lost. Eventually, the events of the war were remembered by some as legend, and forgotten completely by others. Power over the voice would be passed down to the few descendants of the ancient kingdom that were left, and the world of One Piece had found peace again.

I believe that the final battle in One Piece will be the world of One Piece (led by Luffy) vs the Sea Devil itself, in a battle to free the world. Winning the battle would allow the people to reform the sea into its original state, a sea like the one we see on the Earth: more stable weather and magnetic fields that allow anyone to freely navigate it.

But what about the Family of D.’s trump card? How were they able to imprison the Sea Devil in the first place?

Remember that Momonosuke can seemingly only command Zunisha? And that Shirahoshi/Poseidon can only command Sea Kings?

The Family of D. has the ability to command or sentence god, the Sea Devil, itself