‘The following,’ says his translator Willich, ‘are the elements of his _Critique of Pure Reason_, the first of Kant’s systematical works, and the most remarkable for profound reasoning and the striking illustrations, with which it throughout abounds. ‘We are in possession of certain notions _à priori_[8] which are absolutely independent of all experience, although the objects of experience correspond with them, and which are distinguished by necessity, and strict universality. To these are opposed empirical notions, or such as are only possible _à posteriori_, that is, through experience. Besides these, we have certain notions, with which no objects of experience ever correspond, which rise above the world of sense, and which we consider as the most sublime, such as God, liberty, immortality. There is always supposed in every empirical notion, or impression of external objects, a pure perception _à priori_, a form of the sensitive faculty, _viz._ space and time. This form first renders every actual appearance of objects possible. By the sensitive faculty we are able to form perceptions; by the understanding we form general ideas. By the sensitive faculty we experience impressions, and objects are given to us; by the understanding we bring representations of these objects before us: we think of them. Perceptions and general ideas are the elements of all our knowledge. Without the sensitive faculty, no object could be given (proposed to) us; without the understanding none would be thought of by us. These two powers are really distinct from one another; but neither of the two without the other can produce a _notion_. In order to obtain a distinct notion of any one thing, we must present to our general ideas objects in perception, and reduce our perceptions to, or connect them with, these general ideas. As the sensitive faculty has its determined forms, so has our understanding likewise forms _à priori_. These may be properly termed _categories_; they are pure ideas of the understanding, which relate, _à priori_, to the objects of perception in general. The objects of experience, therefore, are in no other way possible; they can in no other way be thought of by us, and their multiplied diversity can only be reduced to one act of judgment, or to one act of consciousness, by means of these categories of sense. Hence, the categories have objective reality. They are either categories of 1. _Quantity_, as unity, number, totality; or, 2. Of _Quality_, as reality, negation, limitation; or, 3. Of _Relation_, as substance and accident, cause and effect; or, 4. Of _Modality_, as possibility and impossibility, existence and non-existence, necessity and contingency. ‘The judgment is the capacity of applying the general ideas of the understanding to the information of experience. The objects of experience are regulated according to these ideas; and not, _vice versâ_, our ideas according to the objects.’