Vital heat

[1] Aristotle would eventually modify this doctrine stating that "sleep is a temporary overpowering of the inner heat by other factors in the body, death its final extinction.

[2] Galen wrote in On the Usefulness of the Parts of the Body (170): "The heart is, as it were, the hearthstone and source of the innate heat by which the animal is governed."

In the 11th century, Avicenna agreed with this notion, stating that the heart produced breath, the "vital power or innate heat" within the body, in his Canon of Medicine.

"This link is not for Aristotle simply an accidental connection, but rather the existence of vital heat is necessitated by the most basic living activity: nutrition.

[5] Although prominent scholars like Aristotle accepted this concept of innate heat and its role in digestion, there were others who were skeptical and retained a different point of view.

Here Plato shows in some detail how in respiration the 'Hot' in us is cooled by the air which enters from outside, and he relies on the cutting power of the fire, which here is identical to the 'Hot', to explain the process of digestion [6] Along with his theory of the role of vital heat in nutrition and digestion, Aristotle believed that vital heat played a role in reproduction which includes several physical parts of the body different from the parts that participate in nutrition.