Answer:
I have all the knowledge you have. But I am so small that I can fit into your hands. What am I?
Without a bridle, or a saddle, across a thing I ride a-straddle. And those I ride, by help of me, though almost blind, are made to see. What am I?
In a tunnel of darkness lies a beast of iron. I can only attack when pulled back. What am I?
I stand in one place yet fill the whole room. I can be filled with molten rock and come in every hue. What am I?
I have a tongue, but cannot speak. I have a bed but cannot sleep. I have four legs but cannot walk. Yet I move as you do. What am I?
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?