P. Coffey, Ontology, or the Theory of Being
“ Again, while efficient causation resolves itself into the categories of actio and passio, the causation of final, formal and material causes cannot be referred to these categories, but neither does it constitute any new category. The influence of a final cause consists in nothing more than its being a good which is the term of appetite or desire. The causation of the formal cause consists in its formally constituting the effect: it is always either a substantial or an accidental form, and so must be referred to the categories of substance, or quality, or quantity. ”
