Answer:
Always old, sometimes new. Never sad, sometimes blue. Never empty, sometimes full. Never pushes, always pulls.
Creatures of power, creatures of grade, creatures of beauty, creatures of strength. As for their lives, they set everything's pace. For all things must come to live. Under their emerald embrace Either in their life or in their death.
Long and slinky like a trout, never sings till it's guts come out.
Brown I am and much admired; many horses have I tried; tire a horse and worry a man; tell me this riddle if you can.
Gets rid of bad ones, short and tall. Tightens when used, one size fits all.
What did the piece of wood say when he saw the screwdriver and screws approaching?
Difficult
Animal
Easy
Food
Funny
Kids
Logic
What am I?