Full Idea
The schema of a pure concept of the understanding is something that can never be brought to an image at all.
Gist of Idea
A pure concept of the understanding can never become an image
Source
Immanuel Kant (Critique of Pure Reason [1781], B181/A142)
Book Reference
Kant,Immanuel: 'Critique of Pure Reason', ed/tr. Guyer,P /Wood,A W [CUO 1998], p.274
A Reaction
Interesting. He is thinking of triangles, for example. The emphasis is on 'pure', and this is a nice defence of the notion of 'pure reason'. Obviously you wouldn't understand a triangle if you were incapable of imagining one.