What was Observation Haki?
It was one of the three types of Haki, a power that allowed one to keenly sense the "presence" of others.
Sensing attacks, predicting an opponent's next move, gauging the strength and emotions of living beings, distinguishing the location and number of objects outside one's field of vision, and more...
These were all basic abilities of Observation Haki.
Those who took it further, such as Fujitora, could even sense whether someone was good or evil, and pinpoint the location of meteors in outer space.
And according to legend, if one trained Observation Haki to its absolute limit, it was even possible to foresee the future!
That was what people knew about Observation Haki.
Lindsey had thought the same way.
But after touching the Stone Gate and experiencing Ancient Observation Haki, his perspective suddenly opened up.
So that was it!
The essence of Ancient Observation Haki was "sheet music"...
Sheet music was a record of musicians.
They wrote notes down on paper, building all kinds of melodies to express different emotions.
Even as time passed, once a melody was set down, it would never change!
The same was true of music.
The "traces" left behind by everything in the world were no different.
They were like countless invisible "lines," whose endpoints were things as they existed in the present!
The ability of Ancient Observation Haki was to capture those traces, allowing its user's perception to travel back along them.
In other words—
To see the past!
"Ordinary Observation Haki can 'sense the present.'"
"The strongest Observation Haki can 'foresee the future.'"
"And the ability of Ancient Observation Haki..."
"Is it to 'peer into the past'?"
Lindsey toyed with the traces around him, curiosity glimmering in his eerie, blood-red eyes.
"How far into the past can