Full Idea
It seems inconceivable how the intuition of a thing that is present should make me know it as it is in itself, for its properties cannot migrate into my faculty of representation.
Gist of Idea
I can't intuit a present thing in itself, because the properties can't enter my representations
Source
Immanuel Kant (Prolegomena to Any Future Metaphysic [1781], 282)
Book Reference
Kant,Immanuel: 'Prolegomena to Any Future Metaphysic', ed/tr. Lucas,Peter G. [Manchester UP 1971], p.38
A Reaction
One might compare this with Locke's distinction of primary and secondary, where the primary properties seem to 'migrate into my faculty of representation', but the secondary ones fail to do so. I think I prefer Locke. This idea threatens idealism.
Related Idea
Idea 16911 Intuition is a representation that depends on the presence of the object [Kant]