The brain floats in our skull • The cerebrospinal fluid serves as a cushion on which the brain rests without the risk of being crushed by its own weight. It protects the brain to the best of its ability against impact (no soccer player would dare kick an old, heavy leather ball with his head, knowing in detail the intricate thing in his head); it does the cleaning and flushing, being one of the most important parts of the glymphatic system.