…hat Vitruvius had written, Leonardo relied on his own experience and experiments, as per his creed. Fewer than half of the twenty-two measurements that Leonardo cited are the ones Vitruvius handed down. The rest reflect the studies on anatomy and human proportion that Leonardo had begun recording in his notebooks. For example, Vitruvius puts the height of a man at six times the length of his foot, but Leonardo records it as seven times.
…e concrete expression to an analogy that went back to Plato and the ancients, one that had become a defining metaphor of Renaissance humanism: the relationship between the microcosm of man and the macrocosm of the earth.