Did you know that William Harvey (1578-1657), the discoverer of the circulation, favored – against Aristotle – the priority and supremacy of blood above all else? Based on his exhaustive experiments with chick eggs, he was convinced that blood appears first during embryogenesis. As such, blood is the “author” and preserver of all viscera, giving rise to and maintaining the rest of the organs, including the heart and brain. The heart may impress with its relentless clock-like propulsive activities, but its very existence and motion (especially in diastole) depend upon the blood from which it derives. Indeed, the heart is formed merely to subserve the blood’s need to spread its inherent qualities – innate heat, spirits, nutriment – to all recesses of the body. As blood is present and moving everywhere, it is the immediate instrument of the soul. The heart, by contrast, is central and instrumental only in so far as it mediates the mechanical distribution of blood’s life-giving forces.
