Answer:
What do you have when you're sitting down that you don't have when you're standing up?
Different lights do make me strange, thus into different sizes I will change.
I am the outstretched fingers that seize and hold the wind. Wisdom flows from me in other hands. Upon me are sweet dreams dreamt, my merest touch brings laughter.
Some live in me, some live on. And some shave me to stride upon. I rarely leave my native land. Until my death I always stand. High and low I may be found. Both above and below ground.
What flares up and does a lot of good, and when it dies is just a piece of wood?
If itβs information you seek, come and see me. If itβs pairs of letters you need, I have consecutively three. What am I?