which deny or explain away all those real and obvious facts of matter on which reasoning must rest, leave little to be said by them on the subject, except that we know nothing either of soul or body, and therefore we cannot say with any certainty what they are: whether they are anything real, whether they are distinct or identical. For them the question, "how are man's soul and body united?" has little value and even little meaning.

Among those theorists who admit real extension as an inherent property of matter, and other qualities and accidents of matter to be just what they are judged to be, as facts, by mankind perceiving them through their senses, there are various and very different hypotheses proposed for explaining the essential constitution of matter or the nature of bodies. The aim of this article does not require, nor would its limits permit, those different systems to be here stated and discussed. It suffices for the purpose and whole object herein intended that all those theories hold the sensible qualities and properties of matter or body to be really what they are perceived through the senses to be.

Among those who admit, explicitly or impliedly, the reality of sensible qualities in matter as conceived by mankind on the testimony of their senses, there is also much diversity of opinion concerning the nature of the union between the human soul and body.

With this class of thinkers it is a common form of expression to style the body "the tenement of the soul," "the prison of the soul," "the instrument of the soul," and the like. The idea of the soul being in the body and ruling over it as an intelligent and living principle is possessed by all; but the manner of its indwelling there is something of which many have but vague and obscure notions. Even in our standard English literature, taken all in all, language often occurs which leaves no doubt of its being a prevailing notion. that the soul's union with the body is an extrinsic one, and not an intrinsic union in composition so as to constitute of soul and body one living substantial nature, one personal being. The soul and body are usually spoken of as acting and reacting on each other, as mutually communicating influences received, etc. But it is plain that those who employ such language conceive the soul and body to have this facility of influencing each other, owing merely to their close proximity, the body being the dwelling-place of the soul, as the room is tenanted by a person, or, perhaps, somewhat as the shell is tenanted by the snail or lobster. In this manner of conceiving the connection between soul and body they are made completely distinct and really separate from each other, having only accidental union that arises from juxtaposition in place. It is thus the "theory of physical influence" explains the union of soul and body in man.

This "theory of physical influence," as it is styled, is usually ascribed to Euler; but its principle had been laid down by Locke before Euler's tine. Locke's language concerning the nature of matter and spirit, and the manner in which they unite in man, was challenged at the time by the Bishop of Worcester, who imputed to Locke materialistic tendencies. Some of Locke's remarks objected to by the bishop, were as follows: "We have ideas of matter and thinking, but possibly shall never be able to know whether any mere material being thinks or no; it being impossible for us, by contemplation of our own ideas, without revelation, to discover whether Omnipotency has not given to some systems of matter fitly disposed, a power to perceive and think, or else joined and fixed to matter so disposed a thinking immaterial substance; it being in respect of our notions not much more remote from our comprehension to conceive that God can, if He pleases, superadd to matter a faculty of thinking, than that He should superadd to it another substance with a faculty of thinking." Book iv., Chapter iii., No. 6.

This passage, along with the defence of it against the bishop's objections, which Mr. Locke subsequently wrote and appended to his "Essay Concerning Human Understanding," led his followers to adopt the principle of "physical influence," in accounting for the connection between the soul and body of man. Euler, who was not born when Locke died,.was the first, however, to propose and defend this doctrine, as reduced to a special and carefully elaborated system under its present name. It is manifest that in this hypothesis, man is not one being, not some one, subsisting in body and soul constituting one nature; but even as man precisely, he is really two beings merely adjoined or associated, with power mutually to act and be acted on; and consequently the theory denies any real unity in man's nature as a rational animal, or as a personal being.

Some theorists have affirmed that it is physically impossible for matter and spirit to have any action and reaction on each other, though they do not directly deny either the spirituality of the soul, or any of the common predicates of matter as generally admitted among men. There are two principal schools of authors who thus think concerning spirit and matter; namely, they who defend the theory of "occasional causes," as best explaining the respective action of soul and body in man, and they who prefer, for that purpose, "the theory of pre-established harmony."

The "system of occasional causes," which is also styled "the theory of assistance," is sometimes attributed to Descartes as its originator, but with doubtful justice; for, others deduce from his language, which, however, in respect to this subject, is not wholly free from obscurity, that he, like Locke, held the doctrine of "phys

ical influence." But this theory of occasional causes, as employed to explain the concurrence or agreement in the actions of man's soul and body, and the mutual dependence which they seem to have, is more correctly ascribed to Malebranche, who, as a fact, proposed and defended it explicitly and at length. According to his hypothesis, when any affections of the soul require corresponding action in the body or its members, and also when any influence is exercised by exterior objects on the body or its senses, which should have corresponding action in the soul, then God Himself, on occasion of this necessity for agreement in the action of man's soul and body, produces, as first cause, the respondent impression or action. The reason given in proof is that neither the soul nor the body can act at all, unless moved to it by the first cause; and still less are they capable of acting on each other, since spirit and matter differ from one another according to their entire species, or in all their specific powers and properties. It is manifest, however, that this reasoning proves too much, and it is therefore null; for, the fact is well known that man's body and soul communicate by action, which is really his own.

Leibnitz also assumed that spirit and matter can have no intercommunication through action and reaction on one another, contrary to what Locke supposed; and, in order to account for the agreement or correspondence of action in the one with action in the other, he proposed the system of "pre-established harmony," according to which, God, in His omniscience and almighty power, so predetermines, orders, and moves all action both of man's body and soul, that they always occur in perfect agreement or harmony. For example, the action of your eye, by which you see the printed words you are now reading, was preordained to be in perfect agreement with the action of your intellect by which you apprehend what the eye sees; the action of your tongue in speaking intelligible words, is foreordained to be simultaneous with that of your mind in thinking the ideas expressed by those words. In this system, then, which was subsequently developed with still more fulness by Wolff, the soul is the complete principle of all action elicited by its powers, without any concurrent influence received from the body, or from external objects acting on the organs of the body. The body is merely an automaton, and the soul would have its action the same, even if it were not connected or associated with the body at all; and, consequently, Newton could have made his famous induction from the falling apple, and demonstrated his theory of gravitation, just the same, even if we make the supposition that his soul and body were then separated, and actually in different hemispheres.

This theory of "pre-established harmony" surely violates the

precept of sound philosophy, which forbids the introducing of the first cause as immediately producing an effect, which can be satisfactorily accounted for by the agency of second causes.

These three theories are sometimes illustrated by an example, in order that their difference may be more clearly perceived; and the example usually chosen for the purpose, is that of two watches which are made to keep precisely the same time, but in three different manners, or by three different means. First, we may conceive these two watches to be kept in exact agreement by some one near them who advances or retards their respective movements, just as required, in order for them always to indicate the same time. The two watches kept together by such means, represent the theory of occasional causes, as applied to explain the concurrent action of man's soul and body. Secondly, we may suppose these two watches to have been made with such perfection that their movements exactly coincide, and they always mark the same time, because of the entire precision with which their own machinery works. The two watches keeping together in this manner serve to illustrate the theory of "pre-established harmony," according to which God so appoints and regulates all operations, both of man's soul and body, that they themselves always act in perfect agreement or harmony with each other, though one of them has no real influence on the other's action. Thirdly, we may conceive the two watches to have their springs and entire machinery so exactly adjusted or fitted to each other that one acts on the other by contact, and their movements are rendered perfectly harmonious through their real action and reaction, one so hastening or retarding the movements of the other as to make their hands denote the same time. This manner of causing the watches to keep the same time, would exemplify the "theory of physical influence,” according to which man's body and soul are so affixed or joined to each other that the action of one really and physically influences the other.

There is a common objection to these three theories for explaining the union between soul and body in man, that seems to be equally conclusive against all, namely, they deny the unity of man's nature as composed of matter and spirit; or, what is the same, they assume that man as a person is made up of two distinct natures that are both complete substances, really existing and acting as such in man. It is plain that no one of these systems admits any substantial union of soul and body constituting man one living substance. But this doctrine contravenes what we positively and certainly know of man as a personal being. We can see in our own conscious and living action that man is one both as a substantial nature and as a person arising from an intimate union of his soul and

body, and not from extrinsic and accidental connection. In accordance with those hypotheses, man, as a person, has only a soul, not a body; his body is an instrument of his soul, but it is not a constituent of his personal being. Against this theorizing stands the fact, however, that man has unity of nature, as a rational animal, and he is one also as a person.1

Any one observing and reflecting on what takes place in himself, must see evidently that the action of his body or of its members is his action in a manner wholly distinct from that in which the action of an instrument, which he uses with his hand, or that of an exterior body moved by him, is his action; for example, the action of the hand that feels, holds, and directs the movements of the pen, is totally different from that of the pen itself. The pen in such case is an instrument which is an entirely distinct agent, and which is complete in itself as a substance; the hand, though acting as an instrument in respect to the person, is nevertheless, a living part of that person, in such a manner that its action is really the action of the person, "actus sunt suppositorum." Consequently, the body and the members of the body are not the soul's instruments in the same sense at all that a pen, cane, and the like are instruments; for, the former are real parts of the person; the latter are extrinsic to the person, and have only accidental connection with the person. Also, sensation is not an act of the body alone, nor is it an act of the soul alone, but of both body and soul as constituting one agent.

No one of these illustrious philosophers first began to doubt obvious facts before "his head became intoxicated with a theory," to borrow the language of Stewart. The speculations of him who devises a new and strange hypothesis, are, in many instances, found to start from mere arbitrary assumptions and foregone conclusions, and in order to maintain consistency with them, the theorist is sometimes required to deny or ignore plain and positive facts in fabricating or working out the details of his fanciful system.

There is good reason for saying, and the assertion seems not too bold, that just as the theory taught in the old schools for explaining the origin of our ideas, with some modifications as to certain accidental particulars made by discoveries in the science of optics, is the one which, after all, best accords with obvious and

1 "Ex anima et corpore constituitur in unoquoque nostrûm duplex unitas, naturæ, et personæ." St. Thomas, 3 part, question 2, a, 1 and 2. There is constituted of soul and body a twofold unity in each one of us, namely, unity of nature and unity of person. Plato held that the soul is united to the body, as the charioteer to the chariot that he drives; Aristotle rejected this notion, and maintained that man's soul is the formal, life-giving principle of his body, constituting, along with the body, one substance.

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