I once heard this story or fable about a man who didn't know what his life purpose was. Somehow he managed to find someone with a big archive of everyones life purpose and he was told his own life purpose again (he fell asleep and had a dream?) When he heard it, he couldn't believe how he'd forgotten it, it was so obvious. He was asked if he wanted a print out, but he declined, saying that now that he remembered it again, there was no way he would ever forget! But then when he woke up, he'd forgotten everything about the dream and his life purpose.

Any idea what story this is, who wrote it or what the origine is? I've been trying to find it for years, but without success so far