Take a good look. It’s always there, part of a healthy, whole hand. Hold up your hand and you’ll see it. The one digit that is pointing the opposite of the other four fingers, every time. Oh yeah, you can force it to go along with all the others, but you do have to work at it. Usually, it just naturally sticks out to the side, like “a sore thumb.” It’s always just a little different and obstinately curving away from all the others - but it sure serves a great purpose.