A study of shifts in scientific strategies for measuring the living body, especially in dynamic systems theory: 1) sheds light on Hegel’s concept of measure in The Science of Logic, and the dialectical transition from categories of being to categories of essence; 2) shows how Hegel’s speculative logic anticipates and analyzes key tensions in scientific attempts to measure and conceive the dynamic agency of the body.  The study’s analysis of the body as having an essentially dynamic identity irreducible to measurement aims to contribute to reconceiving the body, in a way that may be helpful to overcoming dualism.