I answer here from a philosophy of science perspective. The aim is to construct an ontology of dispositions and how they act that makes sense of scientific practice. This leads to a three part ontology – dispositions, activities and manifestations – where arrangements matter. No arrangement → no manifestation. Generally dispositions act in consort, often producing previously undreamt of (possibly even by God) manifestations. The production of manifestations is often in accord with systematic principles, and again arrangements matter: to fix what dispositions act when, what principles are in play, and what a ‘general’/’abstract’ manifestation amounts to in the concrete. So we can, for instance, unlock our doors by raising a weight with a wedge and not just ‘raise a weight with a wedge’.