The Heart - The source of all action
"So the heart is the beginning of life, the Sun of the Microcosm, even as the Sun deserves to be call'd the heart of the world; for it is the heart by whose virtue and pulsation the blood is moved, perfected, made apt to nourish, and is preserved from corruption and coagulation; it is the household divinity which, discharging its function, nourishes, cherishes, quickens the whole body, and is indeed the foundation of life, the source of all action."
William Harvey, 1628