Though we may never be able to comprehend human life, we know certainly that it is a movement, of whatever nature it be. The existence of movement unavoidably implies a body which is being moved and a force which is moving it. Hence, wherever there is life, there is a mass moved by a force. All mass possesses inertia; all force tends to persist
Nikola Tesla (2008). “The Problem of Increasing Human Energy: With Special Reference to the Harnessing of the Sun's Energy”, p.5, Cosimo, Inc.