Answer:
In we go, out we go. All around and in a row. Always, always steady flow. When we'll stop, you'll never known. In we go, out we go.
To unravel me you need a simple key, no key that was made by locksmith's hand. But a key that only I will understand.
I'm the source of all emotion, but I'm caged in a white prison.
Reaching stiffly for the sky, I bare my fingers when its cold. In warmth I wear an emerald glove and in between I dress in gold.
What has to be broken before it can be used?
If it’s information you seek, come and see me. If it’s pairs of letters you need, I have consecutively three. What am I?