Answer:
When the horse strokes the cat, the wood begins to sing.
It cannot be seen, it weighs nothing, but when put into a barrel, it makes it lighter.
What two things can always see what the other sees, but can never see each other?
I love to dance and twist and prance. I shake my tail, as away I sail. Wingless I fly into the sky.
Has no feet, but travels far. Is literate, but not a scholar. Has no mouth, yet clearly speaks.
What goes up the hill and down the hill, And spite of all, yet stand still?