This organ deserves to be styled the starting point of life and the sun of our microcosm just as much as the sun deserves to be styled the heart of the world. For it is by the heart's vigorous beat that the blood is moved, perfected, activated, and protected from injury and coagulation. The heart is the tutelary deity of the body, the basis of life, the source of all things, carrying out its function of nourishing, warming, and activating body as a whole. But we shall more fittingly speak of these matters when we consider the final cause of this kind of movement.

When in many dissections, carried out as opportunity offered upon living animals, I first addressed my mind to seeing how I could discover the function and offices of the heart's movement in animals through the use of my own eyes instead of through the books and writings of others, I kept finding the matter so truly hard and beset with difficulties that I all but thought, with Fracastoro, that the heart's movement had been understood by God alone.

Very many maintain that all we know is still infinitely less than all that still remains unknown.

I avow myself the partisan of truth alone.

Nature is a volume of which God is the author.

As art is a habit with reference to things to be done, so is science a habit in respect to things to be known.

I profess to learn and to teach anatomy not from books but from dissections, not from the tenets of Philosophers but from the fabric of Nature.