When you look into a mirror, what do you see in it's reflection?

A time when I'm green, A time when I'm brown. But both of these times, Cause you to frown. But just in between, For a very short while. I'm perfect and yellow, And cause you to smile. What am I?

I am the invisible paint on the canvas of silence. I can travel through walls without a door and touch your heart without a hand. I am made of math, but I feel like magic. What am I?

Break it and it is better, immediately set and harder to break again.

Ten travelers a-scaling On a range of white and black Each step they take I tremble At a hammer's mighty whack No pitons to assist them Just a staff and cords and keys A harmony of movement Til they rest again at ease