Aristotle of Stagira wrote De Motu Animalium (On the Movement of Animals) in which he geometrically analyzed and described the muscles of animals, this led to the first technical definition of energy. He is regarded as one of the greatest philosophers of all time. Aristotle philosophized on virtually every subject, including logic, philosophy, ethics, physics, biology, psychology, politics, and rhetoric. His work, along with that of other Greek thinkers, laid the foundation for modern science through their inquiries emphasizing logic, reason, and deduction. His work De Motu Animalium (On the Movement of Animals) geometrically analyzed and described the muscles of animals, and translated rotary motion into translatory motion. Aristotle provided the first technical definition of energeia, a word formed by combining two root forms meaning “at” and “work.” He used this term to describe the operation or activity of anything. The modern term 'energy' was ultimately derived from Aristotle's concept of energeia.

Source

• Cleveland, Cutler (Lead Author); Tom Lawrence (Topic Editor). 2008. "Aristotle of Stagira." In: Encyclopedia of Earth. Eds. Cutler J. Cleveland (Washington, D.C.: Environmental Information Coalition, National Council for Science and the Environment). [First published in the Encyclopedia of Earth June 15, 2006; Last revised April 14, 2008; Retrieved July 6, 2009