In this way it will become increasingly clear that in levity we have to do with something which, despite its manifesting characteristics of a 'force' not unlike gravity and thereby resembling the latter, differs essentially from anything purely physical. It is only by its interactions with gravity that levity brings about events in the physical world-events, however, which are themselves partly of a physical, partly of a superphysical kind. Seeing things in this aspect, we are naturally prompted to ask what causes there are in the world which make gravity and levity interact at all. This question will find its answer in due course. First, we must make ourselves more fully acquainted with the various appearances of the gravity-levity interplay in nature.