tinued, till at length it has become possible to conjecture, and at last to establish by satisfactory proof, the existence and character of the physical causes of which our previous generalizations were merely the result and evidence.

To this indirect and circuitous process physical discoverers have necessarily had recourse, owing to the (circumstance that ultimate physical truths are not susceptible of any more direct proof. We can have no direct proof, e. g. of the law of gravitation, or of the laws of motion. We do not find them in our own consciousness, by reflecting on what passes in our minds; nor can they be made apparent to our senses. That every particle of matter in the universe gravitates, each towards the rest, with a force which is directly according to the mass and inversely according to the square of the distance, or that a body once set in motion will, if unimpeded by some counter force, continue for ever in motion in the same direction and with unimpaired velocity,—these are propositions which can only be established by an appeal to the intellect; the proof of all such laws ultimately resolving itself into this, that, assuming them to exist, they account for the phenomena. As, therefore, we are incapable of perceiving directly the ultimate causes of physical phenomena, or the mode of their operation, if these causes are to be discovered at all, they can only be discovered by conjecturing or inferring them from the effects which they produce—in the language of Lord Bacon, by the "interpretation of nature,"

by endeavouring to decipher in the phenomena themselves the causes and laws on which they depend.*

Now in this quality of the higher laws of physical nature-their non-susceptibility of direct proof-we have to note the first and most important point in which the analogy of the physical method becomes inapplicable to Political Economy. In our search after the causes of the production and distribution of wealth, we are not left to conjecture them from the mode of their operation as exemplified in the phenomena of wealth. In order to know why a farmer engages in the

* I may notice here, by the way, the wholly different purpose to which hypothesis is turned in physical and economic science. In the former, hypotheses are the steps by which all great generalizations are accomplished. The several fundamental laws in the different physical sciences, such as the law of gravity, the undulatory theory of light, the atomic theory, were at one time hypotheses in the common acceptation of the word, and have passed through all the gradations of probability, from that of a mere presumption in their favour up to absolute, or nearly absolute, certainty. Even still they differ in no other respect from hypotheses which are more commonly considered as such, than in the greater number and variety of the facts which they explain. In economic science, on the other hand, the ultimate laws (as I have endeavoured to show in the text) being either mental intuitions or physical facts susceptible of direct sensible proof, never pass through the hypothetical stage. Hypothesis here is only useful in the development of principles already established. Thus the diminishing productiveness of the soil being established or admitted, the doctrine of rent is deduced from it by reasoning on a hypothesis framed to suit the object of the inquiry. In the same way, if we desire to ascertain the tendency of any given cause-such, e. g. as the new gold discoveries—we resort to some hypothesis, or assumed case, under which we suppose the principle in question to come into operation; and then, from our knowledge of human motives in the pursuit of wealth, observe the result which will ensue.

production of corn, why he cultivates his land up to a certain point, and why he does not cultivate it further, it is not necessary that we should derive our knowledge from a series of generalizations proceeding upwards from the statistics of corn and cultivation, to the mental feelings which stimulate the industry of the farmer on the one hand, and, on the other, to the physical qualities of the soil on which the productiveness of that industry depends. It is not necessary to do this-to resort to this circuitous process-for this reason, that we have, or may have if we choose to turn our attention to the subject, direct knowledge of these causes in our consciousness of what passes in our own minds, and in the information which our senses 'convey, or at least are capable of conveying to us, of external facts. Every one who embarks in any industrial pursuit is conscious of the motives which actuate him in doing so. He knows that he does so from a view to his own interest-from a desire, for whatever purpose, to possess himself of wealth; he knows that, as far as his information extends, he will pursue his course in the shortest way open to him; that, if not prevented by artificial restrictions, he will buy such materials as he requires in the cheapest market, and sell the commodities which he produces in the dearest. Every one feels that in selecting an industrial pursuit, where the advantages are equal in other respects, he will select that in which he may hope to obtain the greatest profit on his capital; or that in seeking for an investment for what he has realized, he will, where the security is equal, choose those stocks in which the

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rate of interest to be obtained is highest. spect to the other causes on which the production and distribution of wealth depend-the physical properties of natural agents, and the physiological character of human beings in regard to their capacity for increase--for these also direct proof, though of a different kind, is available; proof which appeals not indeed to our consciousness, but to our senses. Thus, e. g. the law of the diminishing productiveness of the soil to repeated applications of capital, if seriously questioned, is capable of being established by direct physical experiment upon the soil, of the result of which our senses may be the judges. If political economists do not perform this experiment themselves in order to establish the fact, it is only because every practical farmer performs it for them. In the case of the physical premises, therefore, of Political Economy, equally with the mental, we are entirely independent of those refined inductive processes by which the ultimate truths of physical science are established.

The grand primary axioms, then, of Political Economy being established by the evidence, which is suitable to them—those of them which are mental by a direct appeal to our consciousness, those of them which are physical by the direct testimony of our senses,—the mode of investigation henceforth to be pursued will in general be analogous to that which is practised in the physical sciences at the same stage-that is to say, after the most important fundamental laws have been established. Guided by this analogy, which now for the first time becomes applicable, our course will be

to develope by means of deductive reasoning the consequences which result from those primary principles in the production and distribution of wealth. These consequences will represent economic laws, which will be true precisely in the same sense in which a mechanical or astronomical law is true, viz. on the hypothesis that the phenomena it describes are not influenced by any disturbing cause, in other words, by some force or principle other than those included in the premises of our reasonings.

In the further prosecution of economic inquiry, our course will still be guided by the analogy of physical science at the corresponding stage. Thus, having by means of deductive reasoning arrived at certain general conclusions, we shall proceed to compare the conclusions thus obtained with existing facts. It is here that statistics come in as a useful and indeed indispensable auxiliary in the discovery of the laws of wealth. You will remember that, when describing on a former occasion the premises of Political Economy, I stated that, besides those cardinal principles which are the predominant forces regulating the production and distribution of wealth, there are certain subordinate influences which also affect very sensibly the general result. The connection of these with the phenomena of wealth is of a much more subtle and recondite character than that of the former principles, and does not readily discover itself to the abstract thinker. In order to the detection of these, it is necessary that attention be drawn to the effects which