The Once-ler dreamt. He dremt that he was among the truffla trees again, that the barbaloots were still climbing to retreave berries, that the humming fish still could hum in the clear waters, and that the swanny swans could chrip without coughing. He dreamt if his first Thneed. He dreamt of his first love. He dreamt of everything, up until his family arrived. then the sweet dream became a nightmare. He, an older and greeder version, arose from the ground. He flinced as the figure reached towards him. the evil figure grabbed his face and made the Once-ler look him in the eye.
"Are you scared?" the figure spoke with a gravelly voice, spewing tar and smoke, "are you scared of what you will become, what you have already become? This is only a dream. Only a short break from the sadness that plagues you. Look what you have done."
The figure left go of his face and turned him. Allowing him to see the Truffla stumps, the tared and gunked river, the smog filled sky. He then turned him to see a familiar sight, his Nora leaving him with the words, "You've become a monster, Mr. Once-ler. An absolute monster."
Then the figure turned him yet again, allowing him to see the animals and the Lorax leave him. Then all his admirers. Then his family. Then the followers. Then, finally, the townspeople built a wall-to not only lock out the destruction, but also their past leader.
The Once-ler awoke with a start and cryed out. He did feel remorse. He certainly did. He had felt it from the moment the Lorax had left, and kept on feeling it to this day. He had thought the stone was meant for his regret, but it wasn't. Someone, not him, had to care. Care and get the townspeople to care. They had to plant the seed. The last seed. The seed the Once-ler had found when he was about to throw himself over the waterfall. And eventally someone, somewhere, would care. And until then, he would stay, and wait, and live with the fear and remorse. Forever.