How can you get very far, If you don't know who you are? How...

How can you get very far, If you don't know who you are? How can you do what you ought, If you don't know what you've got? And if you don't know which to do Of all the things in front of you, Then what you'll have when you are through Is just a mess without a clue Of all the best that can come true If you know What and Which and Who.