In the “Critique of Pure Reason,” p. 67-69; V. 92-94; p. 89, 90; V. 122, 123; further, V. 135, 139, 153, he repeats and insists: the understanding is no faculty of perception, its knowledge is not intuitive but discursive; the understanding is the faculty of judging (p. 69; V. 94), and a judgment is indirect knowledge, an idea of an idea (p. 68; V. 93); the understanding is the faculty of thinking, and thinking is knowledge through conceptions (p. 69; V. 94); the categories of the understanding are by no means the conditions under which objects are given in perception (p. 89; V. 122), and perception in no way requires the functions of thinking (p. 91; V. 123); our understanding can only think, not perceive (V. pp. 135, 139). Further, in the “Prolegomena,” § 20, he says that perception, sensation, _perceptio_, belongs merely to the senses; judgment to the understanding alone; and in § 22, that the work of the senses is to perceive, that of the understanding to think, _i.e._, to judge. Finally, in the “Critique of Practical Reason,” fourth edition, p. 247; Rosenkranz’s edition, p. 281, he says that the understanding is discursive; its ideas are thoughts, not perceptions. All this is in Kant’s own words.
From this it follows that this perceptible world would exist for us even if we had no understanding at all; that it comes into our head in a quite inexplicable manner, which he constantly indicates by his strange expression the perception is _given_, without ever explaining this indefinite and metaphorical expression further.