 One of Kant’s surprising ideas is that each type of objective representation, intuition and concept, can be either empirical or a priori. The idea that some concepts are not empirical may not be surprising because of the famous early modern tradition concerning innate ideas. Of course, Kant’s conception of the origin of such concepts—outlined in what he calls the “metaphysical deduction” (B159, B377)—contains surprises because he does not embrace innate ideas (Longuenesse 1998). But leaving that complication aside, it is surely very surprising to hear that intuition, which in some regards is akin to perception (Parsons 1992, 65–66; Allais 2015, 147ff), can also be empirical or a priori in character. Here it helps to recall that Kant distinguishes sensation from intuition. There remains a question, however, of how we are to understand the very idea that we can have pure—or a priori, i.e., non-empirical—intuition at all. This idea comprises a central piece of Kant’s views on space and time, for he famously contends that space and time are nothing but forms of intuition, a view connected to the claim in the Transcendental Aesthetic that we have pure intuitions of space and of time. This means, as we have seen, that we have non-empirical, singular, immediate representations of space and of time. One goal of this entry is to clarify this idea. It is not a stretch to contend that it represents one of Kant’s most distinctive contributions to modern philosophy. Characteristically, it is profoundly difficult to grasp.