Mind, Formal Principle, Material Principle

Aristotle likens Mind as the Form of Forms, to the hand as the tool of tools.  But a tool is not just ready-to-hand, to borrow from Heidegger; the hand builds it.  Likewise, as Spinoza observes, Mind creates its intellectual tools.  Thus, the relation of Mind to its Forms is twofold: it is their model, and it produces them.  In other words, Mind is both their Formal Principle and their Material Principle, a binarity that is difficult to conceive clearly without the introduction of the latter.