as experienced in ourselves to mechanical agents; and by a creation of the fancy, by a sort of personification of the powers of nature, to invest physical, with the attributes of moral, action. But such indulgence of the imagination is here worse than idle; it has a direct tendency to confuse and entangle the chain of reasoning; and this consideration becomes of more importance in reference to the conclusions founded on physical inquiry. On all grounds, then, we ought surely to keep the search into physical truth as free as possible from such incongruous influence; and soberly investigate physical causes without being misled by the adoption of ideas so foreign to the subject.

Yet notions more or less allied to these have been prevalent among philosophers. This propensity for physical mysticism was pre-eminently fostered in the labyrinths of the scholastic and Cartesian systems of a past age. But the traces of it have not yet been wholly or effectually banished from our schools of science.

Even in later times many philosophers have sought to establish the notion of what they termed a" necessary connexion" or "efficient causation" in natural phenomena; an idea which nevertheless it would appear very difficult distinctly to explain.

It would seem as if they regarded material substances as possessed of some hidden virtues or properties, which confer on them the powers of physical agents; and imagined these occult qualities the

secret soul which animates, as it were, the whole frame of nature.

In some instances, the adoption of these ideas may be traced to associations arising out of the common use of metaphorical language*. We talk of the chain of cause and effect; the links of that chain; the connexion of one event with another; the dependence of causes; the production of a result from its cause. These metaphors being taken from material objects, insensibly lead many minds to suppose some similar, real, and effective union between the events. But this is nothing more than the very common mistake of straining a metaphor beyond the points of parallelism, in which it properly applies, to others which are wholly incidental. Perhaps we might rather say these metaphors themselves have been adopted and conceived upon a false train of analogy. At any rate, if we retain the use of them, we should be careful not to be misled by the phraseology we employ into ideas at variance with the real nature of the relation intended to be expressed by it.

Another source, perhaps, from which these notions of "efficient causation" have derived strength, may be discovered in the vague conceptions which have sometimes prevailed with regard to the nature of mechanical forces. We might instance some speculations on the nature of " inertia," and the commu

* Idola fori.-Bacon.

nication of motion; as well as others connected with the questions once agitated respecting the "vis viva." Or, to take a more familiar example, the indistinct notions which frequently involve in a singular degree of mystery, the advantage obtained in the use of the mechanical powers. On witnessing the effects produced by these contrivances, the untaught mind can hardly help imagining a sort of creative energy which invests matter with new attributes, and supplies a source of active power capable of almost indefinite increase. Scientific investigation, indeed, dispels the illusion, yet it often continues to haunt both our language and our ideas relative to the nature of causation.

Opinions on the Nature of Causation.

WHETHER, however, originating in such misconceptions or not, whether pushed to a greater or less extent, some notions of this kind have prevailed very generally. But reasoners of an opposite school have arisen, who, aiming at a peculiar degree of precision and rigour in their speculations, have utterly denied and discarded all ideas of such active, efficient influence, which, they contend, is altogether chimerical; and have sought to reduce the whole nature and conception of cause and effect to the bare, naked, matter-of-fact, learnt from experience, that some one particular event or phenomenon in nature always invariably follows another in order of

time; the former being termed the effect, the latter the cause; that besides this mere invariable “ se quence" (as it is termed), they have no other kind of connexion or dependence one on the other; all we know or can know of the matter is the simple fact, that such sequence does universally hold good; and that we cannot reverse the order. If we be prone to entertain the idea of any higher or more intimate connexion, this, they contend, is only a vague prepossession, utterly inadmissible in exact philosophic inquiry.

Against these views considerable objection has been raised; often, doubtless, from the abuse of them; because they were too exclusively dwelt upon, or pushed to unwarrantable extremes in their application.

But apart from these objections, the generality of inquirers seem to have felt unable to rest satisfied in a view of the subject apparently so little calculated to gratify the cravings of our intellectual curiosity, and seeming to conduct us to so little an extent into the secret workings of nature which we are so desirous to penetrate. They have generally yielded to the seemingly more natural but vague persuasion, that there is yet in the relation of cause and effect, some real, hidden, essential energy, which pervades and actuates all the operations of the material world.

And some, even of the most truly philosophic minds, have been unwilling wholly to acquiesce in

reducing the notion of causes to what has appeared to them the barren and unsatisfactory relation of a mere invariable junction and sequence of facts; they have been unable to divest themselves wholly of some sort of idea of one event actively occasioning another, and not merely passively preceding it; of an influence of some kind, an intimate connexion, an efficient agency, beyond the bare constancy of a "sequence" or invariable law*.

Physical Causes." Sequence" of Phenomena.

Is, then, physical causation really nothing more than the bare invariable sequence of two facts? To treat the subject fairly, we must of course dismiss, in the first instance, a number of cases which have been often urged against this doctrine, but which the slightest reflection shows to be either frivolous or inapplicable; some such instances are not real invariable sequences of one phenomenon after another; others involve the fallacy of the logician's "non causa pro causâ ;" others are mere statements of the co-existence of two constant properties.

We restrict our view of cause and effect to cases in which some change, either in properties, or in relation or position, occurs; that is, where either some chemical effect or some mechanical motion is produced. To take one or two simple instances of what are properly physical causes and effects: we *See Note C.