Finis est causa causalitatis efficientis, quia facit efficiens esse efficiens: similiter facit materiam esse materiam, et formam esse formam, cum materia non suscipiat formam nisi per finem, et forma non perficiat materiam nisi per finem. Unde dicitur quod finis est causa causarum, quia est causa causalitatis in omnibus causis.
"The end is the cause of the causality of the effective, because it makes the effective to be effective; likewise it makes material to be material and form to be form, since material does not receive form save by the end, and form does not complete material save by the end. Wherefore it is said that the end is the cause of causes, because it is the cause of causality in all causes."
De principiis naturae cap. 4
