Answer:
Whoever makes it, tells it not. Whoever takes it, knows it not. And whoever knows it wants it not
My first is high, My second damp, My whole a tie, A writer's cramp
I weaken all men for hours each day. I show you strange visions while you are away. I take you by night, by day take you back. None suffer to have me, but do from my lack.
I usually wear a yellow coat. I usually have a dark head. I make marks wherever I go.
There are millions of me. I am very small but when moving fast I am deadly.
Black we are and much admired. Many seek us if they are tired. We tire the horse, and comfort man, and turn White when we've fulfilled your plan.