Rapids

Can someone help me interpret this postlude poem? Postlude The Mahayanas tell the story of a sage who once stood on a riverbank looking across at the opposite shore. Although the far side was but dimly visible through the river mists he could se that it was unspeakable beautiful. The hills were green and the trees were all in blossom. So he said to himself, "I want to go there." There was a raft tied at the river's edge. He untied the raft and began to paddle toward the distant shore. The journey was long and hazardous for the currents in midstream were swift. The raging rapids tossed and turned the raft, and he had to work with all his strength to maintain his ballance. From the center of the river both shores were lost from view, and there were times when he was not sure which way he was drifting. But he continued paddling and in due time he reached the far shore. He got out of the raft and said, "Ah, at last I am here. It was a perilous journey, but now I have reached Nirvana." He looked about him. The hills were green and the trees were all in blossom. Then he turned around and looked back. He could not see the opposite shore whence he came. Nor was there any river to be seen. And there was no raft.