That's like asking what's more important for the body; heart or brain.
When the body was first made, all the parts wanted to be the boss.
The brain said, "since I control everything and do all the thinking, I should be the boss."
The feet said, "since I carry man where he wants to go and get him in position to do what the brain wants, then I should be the boss."
The hands said, "since I must do all the work and earn all the money to keep the rest of you going, I should be the boss."
And so it went with the eyes, the heart, the lungs, and all the other parts of the body, each giving the reason why they should be the boss.
Finally, the asshole spoke up and said it was going to be the boss.
All the other parts laughed and laughed at the idea of the asshole being the boss. The asshole got so angry that he blocked himself off and refused to function.
Soon the brain was feverish and could barely think, the feet felt like lead weights and was almost too weak to drag the body anywhere, the eyes grew bleary, and the hands hung useless at the sides. All pleaded with the brain to let the asshole be declared the boss.
And so it happened; all the other parts did all the work and the asshole just bossed and passed out a lot of crap.
THE MORAL: You don't have to be a brain to be a boss, just an old asshole.
Alternate moral: No matter how well things are going, it can all be shut down by a single asshole.