Prevailing Beliefs

To understand the impact that Galen had, not only regarding the circulatory system but also on medicine in general, it is important to look at the prevailing beliefs of the time to feel the scope of the significance of his work. Below you will find some of the more significant ideas that Galen disputes in The Construction of the Embryo and The Art of Medicine.

Galen's Disputes From "The Construction of the Embryo"

Myth: “Philosophers, too have addressed the subject of the construction of the embryo, but have provided no anatomical basis for their statements.” (p.177)
Galen: Galen based much of his knowledge on observation instead of philosophy, unlike many of his contemporaries.

Myth: Erasistratus believed that the arteries do not contain blood. (p.186)
Galen: While Galen did believe that the arteries contained blood, he believed a blood different than that which was created in the liver and carried by the veins.

Belief: According to Plato in Timaeus:
“The heart they have set up in the position of the watchman, as the knot of the veins and fount of the blood which is carried vigorously about all the limbs.” (p. 186)
Galen: Galen uses this to support his belief the heart and the circulatory system carried blood throughout the body. He is careful to qualify this citation with the idea that the ancients referred to all vessels that carried blood as veins.

Myth: Chrysippus and other Stoic and Peripatetic philosophers believed the heart to have been created first in the formation of the embryo and that it was the source of all veins and arteries. (p.187)
Galen: This directly contradicts Galen’s belief that the liver was created first of all organs and that the veins and arteries were formed by the sperm after conception.

Myth: Herophilus asserted that organs grew from one another. (p. 189)
Myth: Some believed that the heart was created first and that the heart formed other parts of the body. (pp. 188-189)
Galen: Galen believed that the veins and the arteries were responsible for the creation of the other major organs in the body and that the liver was created first in the embryo.