Innate heat is a fundamental concept in Galenic medicine, referring to a physiological heat proper to living beings. Originating in the heart, it takes part in the vital and organic functions of the human body. As instrument of the soul, it animates the body in a similar way to a bodily flame. Its nature and role is bound up with the definition of life within a theoretical framework combining natural philosophy and medicine. Consequently, physiological debates on innate heat often converged on cosmological, chymical, and embryological considerations on the origin, composition, and transmission of life.
In Renaissance Galenism, innate heat is traditionally described as a bodily substance of a subtle nature, transported by the spirit, and transmitted at birth through the seed. It is also related to the radical moisture, so that the calidum innatum often refers to the vital substance formed by the spirit, the innate heat, and the radical moisture. Within the human body, the innate heat is sourced in the heart and cooled down by the inspiration of air in the lungs during breathing. At the same time, it is spread through the whole body to operate the vital functions. In particular, it is the instrument of the vegetative soul in order to achieve the physiological operations of generation, growth, and nutrition – mainly digestion and coction. It is also in charge of forming the vital spirit in the left ventricle of the heart.
KeywordsMedical Theory Elemental Substance Nutritive Function Medical Debate Vital Substance
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