"Life is water dancing to the tune of macromolecules", stated Albert Szent-Gyorgyi, medicine Nobel Prize winner in 1937. Proteins can influence their hydration water dynamics and structure. Conversely water molecules can control the shape and function of proteins and consequently also the cell biology and metabolism. Hydration dyna-mics can be a regulator for cell activity and can even shut down cell metabolism completely under extreme conditions. The author shows that proteins and their hydration water molecules highly influence each other, their motions are coupled. The result is a dynamic interplay, a dance to the same tune at terahertz frequencies, of high importance to the cell and life in general.