Kant writes: "Since, then, the receptivity of the subject, its capacity to be affected by objects, must necessarily precede all intuitions of these objects, it can readily be understood how the form of all appearances can be given prior to all actual perceptions, and so exist in the mind "a priori"" (A26/B42). Appearance is then, via the faculty of transcendental imagination ("Einbildungskraft"), grounded systematically in accordance with the categories of the understanding. Kant's metaphysical system, which focuses on the operations of cognitive faculties ("Erkenntnisvermögen"), places substantial limits on knowledge not founded in the forms of sensibility ("Sinnlichkeit"). Thus it sees the error of metaphysical systems prior to the Critique as failing to first take into consideration the limitations of the human capacity for knowledge. Transcendental imagination is described in the first edition of the "Critique of Pure Reason" but Kant omits it from the second edition of 1787.