Full Idea
Kant maintains that it is impossible to draw a suitable distinction between the cognitive and sensory 'elements' in sensory experience.
Gist of Idea
Kant says the cognitive and sensory elements in experience can't be separated
Source
report of Immanuel Kant (Critique of Pure Reason [1781]) by Jonathan Dancy - Intro to Contemporary Epistemology 8.4
Book Reference
Dancy,Jonathan: 'Introduction to Contemporary Epistemology' [Blackwell 1985], p.120