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imposed upon, the impressions received from sense, constitute knowledge, or make experience possible. In this way he sought to finish the work commenced by Locke, - to discover the grounds and origin of human knowledge, and thence to deduce the conditions of its use, and to determine its extent and boundaries. Perhaps we may gain more accurate notions of the execution of this task, by going back for a time to the theory of his predecessor.

The change of a preposition is sufficient to reconcile the leading doctrine of Locke with the opinions of those philosophers, who have most distinguished themselves by the virulence of their attacks upon his system. The proposition, as he states it, that all our knowledge proceeds from sensation and reflection, as it implies that we are not to go behind these faculties in accounting for its origin, is faulty in itself, and at variance with his subsequent assertions. Had he asserted, that all truth is perceived through these faculties, or first known on occasion of their exercise, he would not merely have avoided misapprehensions and unfounded complaints, but have stated an undeniable fact, which not the most illiberal of his opponents could ever dream of controverting. The two worlds of matter and mind are the only possible objects of human cognition. We can know the one only through the functions of sense, and the other through the exercise of that faculty, - call

it reflection, consciousness, or what you please, - by which we cognize objects of pure thought, or the immaterial creation.

But if we merely trace given idea to sensation or reflection, we leave the matter short; we have not fully accounted for its origin. An impression is made on the senses, and a perception of the understanding immediately follows. Is there not an element in it, which is purely in. tellectual, and as such, not caused by the action on the

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nerves, though this action may mark the occasion, on which it rises ? The eye gives us a perception of distance, though the impression on the optic nerve certainly transmits to the mind nothing but a sensation of various colors. The judgment immediately adds an estimate of the distance, at which the visible object is placed ; and does this, from long practice, with such facility and quickness, that we confound the act with the sensation, and imagine that we see the separation of bodies in space. Thus we falsely attribute to the sensation more knowledge than really proceeds from it. Still, this is an instance not of original mental action, but of an acquired perception, founded on habit, and as such is noticed by Locke, as perfectly consistent with his hypothesis. But are there not other instances, where the tendency to add something to the sensible impression is original, instinctive, and acts with irresistible force; and where the addition made, or the subjective element, as the Germans call it, is wholly unlike any quality existing in the outward thing, and can in no way be traced to its influence ?

To answer this question, we take an example most familiar to metaphysicians. Two events happen in close connexion, and we immediately connect them by the sup.. posed relation of cause and effect. The hand is held near the fire, and the sensation of pain follows. Heat is abstracted from water, and the fluid immediately congeals. Certain solid substances are thrown into water, and they straightway dissolve, the fluid remaining transparent as ever; other substances in powder are thrown in, the medium remains turbid for a time, and then the foreign matter sinks unchanged to the bottom. Now, in each of these cases, we immediately and necessarily suppose, that the first event is an efficient agent, and of its own power or force produces the second. But the senses tell us nothing

of such a connexion. They only inform us of the two events themselves, and that they are contiguous in place and time. Nor can the judgment be attributed to reasoning, or a power of tracing the relations between ideas.) For what resemblance is there between the ideas of heat and pain, between those of cold and solidity, between pounded sugar and transparency in water, or pounded alabaster and insolubility ? None at all. Naturally and easily as we make the transition now from one of these related ideas to the other, had we no previous experience, - had we never seen the experiment or heard of its being tried, - we should no more have thought of connecting the two notions, than of tracing an analogy between a thing a yard long and one that is red. The two ideas are wholly dissimilar.

The whole matter may be summed up as follows; that, having sensible evidence of two events happening in direct succession, we immediately connect with them the idea of power, or efficient agency. Whence comes this idea? Certainly not from sensation. We do not perceive the power of fire to melt lead or consume paper, just as we perceive its light and the flickering of its flame, merely by looking at it. We perceive the fact, indeed, that the lead is melted and the paper is dissipated; but the supposition, that the fire CAUSES this result, goes beyond the perception, is extraneous to it, and, so far as the senses are concerned, is entirely gratuitous. Does it come from reflection then ? This faculty denotes nothing but attention to the subjects of our consciousness, and we surely are not conscious of the powers of material things. Consciousness informs us, indeed, that the idea exists in the mind, but tells us nothing about its origin ; nor can we trace any

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process, or train of thought, which seems to end in giving birth to this notion. The idea of power, therefore, is a fair instance of an element of knowledge, in itself universal and of

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primary importance, the origin of which cannot be ascribed either to external or internal experience.

Now, this instinctive yoking together of two events as cause and effect, or rather the universal judgment closely related to it, “ that every thing which happens must have a cause,” is termed, in the elegant language of Kant“ a synthetical judgment a priori.”)(Propositions are called analytical or synthetical, according as they are either merely explanatory, and add nothing to the sum of our knowledge, or as they have an amplifying effect, and actually enlarge the given cognition. In other words, the predicate of an analytical judgment affirms nothing but what was already contained in the idea of the subject. This is the nature of a complete or partial definition. Facts which we learn from experience are instances of synthetical judgments, the predicate going beyond the subject, and thus making a positive addition to our stock of previous knowledge. The proposition we have been considering at such length is evidently synthetical, for there is nothing in the

very conception or idea of one event to create a necessity of its being preceded or followed by another of a different character. It is also called a judgment a priori, because, as we have seen, it is not, and it cannot be, derived from experience. Then what is its real origin? How do we obtain it ? This is Hume's problem. Make the question universal, state it in the broadest possible form, and we have the great problem of the Transcendental philosophy ; “How are synthetical judgments a priori possible ? ” The expression is not remarkable for perspicuity, but the meaning is this ;(How is it, that, independent of experience, we are able to know any thing with absolute certainty? To

Το the consideration of this question, the “ Critique of Pure Reason” is exclusively devoted. We first seek for a criterion, by which we may securely

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distinguish a priori knowledge from that which is founded on experience. Kant finds such a test in the characteris. tics of universality and strict necessity, neither of which can be attached to any propositions of empirical origin. Human experience is never complete,

never exhausts the possible variety of cases; its judgments, therefore, are never universally true or demonstratively certain ; but, founded on an inductive process, they are valid so far as our observation has extended. The contrary is always pos. sible and conceivable. Not so with all the propositions of mathematics, with some axioms in physics, and with many other truths, that are implied in all the forms of speculative knowledge. These carry their own evidence along with them, the denial of them involving a contradiction or absurdity, and no case being supposable where absolute and universal certainty would fail to attend them. There. fore, they are not derived from experience, and the ques. tion recurs with regard to their origin, Whence does the mind obtain them?

Kant defies the world to give any other answer to this query, than that which we have already stated as the foun. dation of his system ;— that they are forms of the mind itself, — the colored medium through which we look out upon the universe of cognizable things. The material world is deaf and dumb to such truths. The mind does not derive them from without, but from its own stores, by its own inborn energy imposes them as necessary

and immutable laws upon the outward universe. Our percep. tive faculties have a peculiar organization, and can act only within well-defined limits. Therefore we know a priori, that the information received through the senses must conform to this organization, and receive certain changes from the passages, through which it is transmitted In what manner objects would appear to beings of a different con

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