 A main tenet in Kilwardby’s ontology is that every thing that exists outside the soul either exists in an individual or is itself an individual (QLIIS 17, 64). As all substances are composites of matter and form, matter and form are the two possible causes of individuation. It cannot be matter on its own because matter receives its determinations from form. It could be form, but in this case it would be either accidental or substantial form. He promptly dismisses the first possibility, since accidents can only inhere in an already constituted primary substance, that is, they follow the constitution of an individual substance rather than explain the constitution of that substance as an individual. This is not to say, he points out, that there are individuals without accidents: a sublunary, corporeal individual is always temporally and spatially located, even though one can think of an individual without reference to this particular place and time (QLIIS 17, 68).