At Gray Institute®, there is a constant search for the TRUTHS (or Principles) of human movement. The Truths / Principles serve as the basis of the Strategies we use to train or rehabilitate patients / clients. Truths are lawful ways that the body behaves in our environment. These Truths or Principles should transcend the type of movement. They should be the same for the different limbs, joints, or muscles that make up the human “machine.” This paper provides a perspective beyond human function that forces us to consider Principles that transcend species. Its specific focus is the properties of muscle-tendon units that allow us to walk, run, and jump efficiently.