in his Critique of Pure Reason he undertook to demonstrate that neither reason nor sensory experience was by itself sufficient for the acquisition of knowledge: both were essential. According to Kant, it was true that human cognition necessarily conformed to an underlying framework of a priori forms and concepts which were imposed by the mind upon the data supplied by the senses; at the same time, the legitimate application of these was confined to the sensory sphere and any attempt to extend them to establish truths concerning what obtained outside that sphere must always be unjustified.
Immanuel Kant
