After fifty years of isolation, Brook's mind was a very strange place. Sometimes he saw things that were not there (though he had no eyes) and heard the singing of those who had been dead for decades. His dreams were vivid and colorful and felt so very real, and there were times when he fell asleep it felt like he had just woken up.
Brook's nightmares were just as strong, and there were nights he felt like he was trapped in his own insanity.
But dreams—good and bad—never lasted, and even if they never went away entirely, the longer he traveled with the Straw Hat Pirates the less he saw of the ghosts of his past. There was much to be said about the benefits of sunlight to a man's soul, and for the first time since his death Brook felt truly alive.
It seemed impossible to think that he would ever be free of the Florian Triangle, much less have a second chance at fulfilling his promise. To think that Laboon was still waiting and that Luffy had met him would have been unbelievable had Brook not heard it with his own ears (though he had none).
Maybe he was only living a dream and someday he would wake up surrounded by the mists and the horror of Thriller Bark. Maybe the Straw Hat Pirates were nothing more than a cruel fantasy constructed by an insane skeleton. Or maybe he was nothing more than a dead man walking in a world only meant for the living.
Brook's mind was a strange place. He concentrated on living each moment to the fullest, because if he didn't he would retreat to the dark recesses of his soul, the pit where each of his nightmares was born. He had to fight, just like he had fought every day for fifty years, for the reality which was his present, because if he didn't he would only lose himself in his past.