Matthew Boyle relates Kant’s account of cognition to Aristotle’s hylomorphic theory of substance. On Aristotle’s view, the form of a substance is the ground of its existence. To know this form is to know those of its properties without which it cannot exist. These characterize the substance as it is in itself. Such knowledge of form amounts to knowledge of a thing in itself, and the view that such knowledge is possible for us might be called formal realism. Kant thinks that this requires a type of mind human beings do not have: a non-discursive intellect. Boyle argues that Kant transposes Aristotle’s hylomorphic framework from a formal-realist to a formal-idealist register, and so “internalizes” the form-matter contrast. Instead of speaking of forms of being qua being Kant speaks of forms of objects insofar as they are knowable by a finite intellect. For Kant, just as for Aristotle, the form of a thing is its essence (and thereby the ground of its intelligibility). But for things whose form is ideal – appearances – knowledge of form cannot amount to knowledge of the ground of their existence. It can only amount to knowledge of the ground of their knowability.