Traditionally, motion used to be attributed to a causal agency. This view became a fundamental principle in Aristotle’s organic physics that dominated Western science for centuries. Newton’s radical attempt to replace Aristotle’s organic science for an agent-free physics has failed. Gravity defied explanation because it manifested itself as “action-at-a-distance” and Newton could not find other solution for this fact except divine intervention. The introduction of field theory in physics provided a means to eliminate agency and resolve the “action-without-contact” puzzle. In biology, there is no need to eliminate agency but the concepts of action and field (field of action flow) do play an important role in explaining the fluidity of motion. The talk outlines a generic theory for perceptual control of animal motion and presents a few experimental findings with a special focus on diffusion fields.