Clearly chosen for its value as scientific literature and historical context, Harvey's work also shows a better understanding of anatomy than one might otherwise expect from the mid 1600's. He refutes the then current view that the lungs connect directly to the right side of the heart, filling that cavity with air but only goes so far as suggesting the need for further investigation as to why the lungs could need so much blood supply. The path of blood, purpose and function of valves, differences between arteries and veins -- these were all discovered by that time. He also demonstrates a clear understanding of the full spectrum of animals in showing the differences and similarities in their circulatory systems. ( )