But much important reasoning on every subject except pure mathematics is necessarily carried on that never aims at demonstration; indeed the greater part of our reasoning is of this kind. It would put an end to almost all practical reasoning to require the reasoners to begin by accurately defining genera and species. Suppose, for example, the object of inquiry, or of proof, is whether zoophytes be animals or plants. To treat the subject syllogistically, so as to arrive at certainty, the inquirer must commence by an accurate definition of what he means by plants and what by animals. And having the properties of the zoophyte in view, he might frame his definition so as to include these properties, or to exclude some of them. And thus one logician might prove it to be a plant, and another logician might prove it, by a syllogism equally conclusive, to be an animal. The dispute, therefore, between them is the major term. One says all animals have certain qualities or attributes; zoophytes have these qualities or attributes, therefore zoophytes are animals.* The other retorts, all vegetables have such and such qualities, zoophytes have these qualities, therefore zoophytes are vegetables. They may then try what negatives will do. says, no vegetable has attributes such as voluntary motion, zoophytes have voluntary motion, therefore zoophytes are not vegetables. The other retorts, no animal is fixed by a root to a particular spot, zoophytes are so fixed, therefore they are not animals. Thus, by the definitions that they adopt of animal and vegetable, they may prove them first to be both animals and vegetables, and then, with equal clearness, to be neither vegetables nor animals. We say nothing of the disputing of the facts stated on each hand, that is the minor premisses of the syllogisms, namely, whether zoophytes have the

One

* This and the following syllogism are scarcely warranted logically in the conclusion.

attributes alleged on either side; for it is not the business of reasoning to ascertain facts, but merely to class them when ascertained. Naturalists, as it appears to us, do not proceed by definitions and syllogisms to the determination of this point; but taking a general view of the characteristics of plants and animals, and leaving the definition of the classes animal and vegetable, to be afterwards determined if necessary, and perhaps to be modified by their very investigation of the nature of zoophytes, they proceed directly to compare zoophytes with animal properties on the one hand, and with vegetable properties on the other, and so, upon the whole, to form a mere opinion as to the class to which they should be allotted. By the name which they have given them. they confess their inability, in the present state of our knowledge, to fix their class; and the result may be that some zoophytes may come to be regarded as animals and some vegetables.

The Linnæan system of botany seems to be one which might be reasoned out by syllogisms. As, for example, all plants having so many pistils and so many stamens. belong to a certain class and order, all lilies have that number of pistils and stamens, therefore lilies, &c. The natural system seems scarcely to be susceptible of definitions so accurate as to form the basis of syllogisms; but is formed by a direct comparison of each species with several orders and genera approximating in their general qualities, and the species is classed according to its greater similarity in the most important attributes with one genus rather than with any of the other genera.

Or, let us look at our former example of comparing lightning with magnetic attraction, by comparing each with electrical phenomena. To proceed syllogistically, the logician must begin by defining what precisely he includes in the phenomena of lightning. In this he will encounter some difficulty; for if he include light and heat, he will be in danger of including the

phenomena of combustion. If, to avoid this, he introduce the notions of suddenness and violence, he would not so get rid of explosions, which are sudden and violent. He must also define what he means by the phenomena of magnetism, in which he would also find difficulty, as he might confound it in his definition with the attraction of gravitation or of cohesion. He must also define his middle term, electrical phenomena, and here he would encounter fresh difficulties; for if he included in it friction, he would exclude the galvanic or voltaic phenomena. But having got over these difficulties, he is prepared to march to his conclusion with infallible demonstrative certainty. Natural philosophers, however, would find the necessity of constructing such definitions an intolerable hindrance to such inquiries. They, therefore, compare the general phenomena of lightning with those of electricity, and those of electricity with those of magnetism; and by observing the differences between these different classes of phenomena and those of combustion on the one hand, and those of gravitation and cohesion on the other, they, without pretending to demonstration, come to the opinion that lightning and magnetic attraction proceed from the same cause. Whether light, heat, combustion, gravitation, are or are not to be ascribed to the same cause, they leave to be determined by future discoveries of phenomena.

Reasoning on subjects in which mind occurs among the objects of it, will be noticed under a future division of our work.

The use of language in intellectual operations respecting external material objects.

We are not here to consider the use of language in communicating thoughts to others, or informing other minds, but to glance at its use in intellectual operations which have for their objects sensations and perceptions.

In classification names assist us in regarding a class as one defined whole, like an individual, different from all other individuals. We class objects we have seen by the resemblances indicated by the similarity of the sensations which they excite, separating them from other objects by their differences from them, indicated by the differences of the sensations excited by them. But without names for the classes, we should confound objects belonging to different classes, as often as we might observe resemblances between them, without attending at the moment to their differences. But the name of the class limits the attributes which characterise it, or the objects which belong to it by possessing these attributes, and enables us to recal the class without difficulty, and to present it before the mind as one whole, of which the various objects that belong to it are parts, or (according to another view), of which the various characteristic attributes of it are parts. The term "mammalia," for example, immediately suggests those animals that suckle their young, as distinguished from other classes of animals, such as birds, fishes, reptiles, &c.; or it suggests to us those attributes that characterise the class of mammalia, as distinguished from other classes of animals. The name presents the class to the mind as one whole-an individual, and thus gives precision to our thoughts respecting it, and greatly aids us in determining what animals belong to it.

So the name "attraction " recals a particular class of phenomena as one whole, of which different kinds of attraction, as the attraction of gravity, the attraction of magnets, electrical attraction, are component parts, and prepares us for separating these different kinds of attraction, by their differences, into different classes, and for reasoning upon them.

Similar facilities are afforded by language in induction and reasoning. Names given to phenomena recal events in their connection of antecedents and consequents, or

their relation of cause and effect, and enable us to compare them with the remembrance of other phenomena. And as reasoning about external material objects is one mode of ascertaining or demonstrating the class to which any object or phenomenon belongs or does not belong, names given to classes of objects or phenomena are so important in all reasoning respecting them, that without such names the mind could scarcely arrange them under classes or genera.

The influence of language in imagination or conception.

We have introduced imagination or conception for the first time in this connection, because we are convinced that the operation or exercise of mind which is known by these names, as employed about material external objects, so far as it is different from memory, depends greatly, if not entirely, on the use of language.

We have heard conception or imagination distinguished from memory, on the ground that memory always includes the notion of past time, at which the remembered sensation or object was experienced or perceived. But former sensations, or objects formerly perceived, may be recalled to the mind without any notion of their having been previously in the mind; and surely it is not a sufficient reason for classing the same state of the mind, the same recalled sensation or perception, under different powers of the mind, according as it is or is not accompanied with the consciousness that it is a remembrance of what we have formerly experienced. Many scenes recur to the mind of which we cannot tell where and when we saw them, or whether we ever saw them, which yet are scenes which have formerly been subjects of thought in the mind. A particular scene is familiar to us, having frequently presented itself in dreaming, so vividly that we could draw it, which for a considerable time we could not remember when we had seen it, or