TO THE MOST ILLUSTRIOUS, AND MOST CLEMENT

Prince, Cosimo de' Medici, Duke of the Tuscans,

Best and Greatest, Andrés Laguna,

of Segovia, Medical Doctor,

Knight of Saint Peter.

A large historiated woodcut initial 'H' depicts three cherubic figures or infants in a landscape; one is seated, one is leaning against the letter's frame, and a third is visible in the background.

The divine Plato proclaimed, most clement Prince, that the structure of the human body is similar to a well-ordered city, and he was not wrong. For if we accurately weigh the constitution and arrangement of both, we will find nothing clearly in a city that is not also contained, far more abundantly and perfectly, within the human body. Indeed, every strongest city is accustomed to being surrounded by a sturdy wall, by which the incursions and assaults of enemies are warded off. In place of a wall, the human body has the outer skin, which protects it from external injuries. Those who wish to make a city impregnable and least liable to plots, best leaders always allow only one wide gate for it, which is the path for receiving provisions: but many channels and aqueducts, for purging its waste. Similarly, Nature also [has] a mouth...