That you are a once-in-all-history event.

是不是这首歌阿~
Steps To Happiness
Everybody Knows:
You can't be all things to all people.
You can't do all things at once.
You can't do all things equally well.
You can't do all things better than everyone else.
Your humanity is showing just like everyone else's.
So:
You have to find out who you are,and be that.
You have to decide what comes first,and do that.
You have to discover your strengths,and use them.
You have to learn not to compete with others,
Because no one else is in the contest of *being you*.
Then:
You will have learned to accept your own uniqueness.
You will have learned to set priorities and make decisions.
You will have learned to live with your limitations.
You will have learned to give yourself the respect that is due.
And you'll be a most vital mortal.
Dare To Believe:
That you are a wonderful,unique person.
That you are a once-in-all-history event.
That it's more than a right,it's your duty,to be who you are.
That life is not a problem to solve,but a gift to cherish.
And you'll be able to stay one up on what used to get you down.
如果是这首歌的话~
鉴于这句话所处的语境~可以翻译成 你的存在是世界历史唯一的壮举!
字面翻译是 你是历史上出现过唯一的现象!
应该是带有爱情色彩的~前面那句话说得是你是唯一的~独一无二的~