Substance, body and accident have different natures: a colour may subsist in a body, while a body is not itself an accident of colour. Nevertheless, ordinary speech and perception allow both the body and its colour to be seen. It is therefore disputed whether the specific nature of body or accident is a necessary condition of all seeing.
The argument does not claim that substances and accidents share every property. It proposes that the relevant object of vision might be broader than their particular essences. No bodily feature is thereby attributed to God.