Answer:
Without a bridle, or a saddle, across a thing I ride a-straddle. And those I ride, by help of me, though almost blind, are made to see.
What is lighter than what it is made of?
I always run but never walk, I sometimes sing but cannot talk, No head on which a hat to place, You always look me in the face.
At the sound of me, one may dream or stamp their feet, At the sound of me, one may laugh or sometimes weep.
I am whole but incomplete. I have no eyes, yet I see. You can see, and see right through me. My largest part is one fourth of what I once was.
It can be cracked, It can be made, It can be told, it can be played. What is it?