Answer:
What can be measured but not seen?
Two brothers we are, great burdens we bear. All day we are bitterly pressed. Yet this I will say, we are full all the day, and empty when go to rest.
Being able to interpret the letters on this screen proves that you have this quality.
I bind it and it walks. I loose it and it stops.
What 8 letter word can have a letter taken away and it still makes a word. Take another letter away and it still makes a word. Keep on doing that until you have one letter left. What is the word?
If itβs information you seek, come and see me. If itβs pairs of letters you need, I have consecutively three. What am I?