On the other hand, the universal common nature of all phenomena of one particular kind, that which must be presupposed if the explanation from causes is to have any sense and meaning, is the general force of nature, which, in physics, must remain a qualitas occulta, because with it the etiological explanation ends and the metaphysical begins.
Aitzitik, orokorra, mota determinatu bateko agerpen guztien esentzia komuna, zeinaren suposiziorik gabe kausatiko azalpenak ez bailuke zentzurik eta esanahirik izango, hori natur indar orokorra da, fisikan qualitas occulta gisara egon behar duena, hain zuzen hor azalpen aitiologikoa amaitu eta metafisikoa hasten delako.