Full Idea
That which allows the manifold of appearance to be intuited as ordered in certain relations I call the 'form' of appearance.
Gist of Idea
Appearances have a 'form', which indicates a relational order
Source
Immanuel Kant (Critique of Pure Reason [1781], B034/A20)
Book Reference
Kant,Immanuel: 'Critique of Pure Reason', ed/tr. Guyer,P /Wood,A W [CUO 1998], p.155
A Reaction
An important idea, which figures prominently in Wittgenstein's Tractatus. Presumably the noumenon is responsible for generating the form in the appearances, and we infer the order of the world thereby (though we can't prove it).