The Natural Faculties (Powers of the Body)
Why does the body nourish and grow itself? Galen answers: each organ wields innate powers — to attract, hold, transform, and expel.
Galen taught that living bodies are not mere machines but are animated by inborn "faculties" — powers that belong to each organ and tissue. He named four key ones: an attractive power that draws in what the part needs, a retentive power that holds it, an alterative power that transforms it (as the stomach concocts food), and an expulsive power that voids what is useless. Against atomists who explained the body by blind matter in motion, Galen insisted these purposeful powers prove that Nature does nothing in vain.
Key passages(4)
De causis et signis diuturnorum morborum libri duo · Aretaeus of Cappadocia
De curatione diuturnorum morborum libri duo · Aretaeus of Cappadocia
De causis et signis diuturnorum morborum libri duo · Aretaeus of Cappadocia