Kant's picture of the human person anchored persons much more firmly in the sensible world than was true of most philosophers of his time, yet he also populated the mind with a rich array of freedom-conferring, non-experiential cognitive equipment. Strangely, he argued for the two sides of this duality together very rarely. The neglected Appendix in the first Critique, The Amphiboly of the Concepts of Reflection, is one such place. Here he argues that our experience must have elements that we could get only via our senses and yet that we must apply highly sophisticated concepts to what the senses deliver if the results are to be conscious experiences. The concept of numerical identity, not discussed anywhere else in the first Critique, is foremost among them.