Answer:
Until I am measured I am not known, Yet how you miss me when I have flown.
I am a precious little thing, dancing and eating all the time. Watch me from a distance, so you can feel my warm and gentle love. But don't come to close or my next meal you could be!
Who is it that rows quickly with four oars, but never comes out from under his own roof?
It flies when it's on and floats coming off.
Talks like this, a green wise man does. Guess my clue, you will.
You can always find me in the past. I am created in the present, but the future can not change me. What am I?