Position ... movement ... linked through conservation of energy. If we conceive of the potential energy surface of a system as the set of forces responsible for form in a biological system, then movement or momentum over the surface, the kinetic energy, is function. Movement is kinetic energy, and motion is tied to spatial dimension as a function of time. The arrow of time is related to entropy and is the natural direction of all systems. Time and energy. Position and momentum. These fundamental properties of natural systems are the building blocks of biological form and function. We will see that these properties of systems are complementary and have very important philosophical and epistemological consequences in our understanding of biological systems. We can not understand a biological system if we can not appreciate its motion in state space. The study of motion is the study of mechanics. Whether the motion is an actin molecule or an atomic orbital, there are just several basic motions that sum up the majority of the mechanical actions in all biological systems.