perception contains very much more than the co-ordinated. sensations immediately experienced. Along with these there go the remembered visual impressions produced by such a surface, which cannot be kept out of the mind, and in the suggestion of which the perception largely consists; and there are automatic inferences respecting the texture and density of the substance. Again, when gazing at some one object, it will be found that objects on the outskirts of the field of view are recognized more by representation than by presentation. If, without moving his eyes, the observer will consider what is contained in his direct consciousness of these outlying objects, he will find that they impress him simply as ill-defined patches of colour; that were it not for his previous experiences he would not know the meanings of these patches; and that in perceiving what the objects are, he ekes out the vaguely-presented impressions with some comparatively-distinct represented ones. What thus manifestly happens with perceptions of this order, happens in one form or other with all perceptions. In fact, when analyzed to the bottom, all perceptions prove to be acquired perceptions. From its simplest to its most complex forms, Perception is essentially a diagnosis.

$355. To express most generally the truth that has been variously illustrated in detail-Perception is a discerning of the relation or relations between states of consciousness, partly presentative and partly representative; which states of consciousness must be themselves known to the extent involved in the knowledge of their relations.

Under its simplest form ( a form, however, of which the adult mind has few, if any, examples) Perception is the consciousness of a single relation. More commonly, a number of relations are simultaneously presented and represented; and the relations among these relations are cognized. Most frequently, the relations of relations of relations are the objects of perception; as when any neighbouring solid body is

regarded. And very often-as when observing the motions of an animal, which are known to us as the relations between certain highly-complex relations of position now present and certain others just past—a still more involved relativity is contemplated.

Further, it is to be noticed that in the ascending grades of Perception there is an increase not only in the number and complexity of the relations grasped together, but also in the variety of their kinds. Numerous relations of position, of extension, of coexistence, of sequence, of degrees in all sensible qualities, are co-ordinated in one thought; or what appears to us such.

Add to which that, as heretofore pointed out in each special case, the act of perception is the establishment of a relation of likeness between the particular relation or group of relations contemplated, and some past relations or groups of relations-the assimilation of it to such past relations or groups of relations-the classing of it with them.

§ 356. It now remains only to apply the analysis thus far pursued to the relations themselves. By successive decompositions we have found that our intellectual operations are severally performed by establishing relations, and groups of relations, among those undecomposable states of consciousness directly produced in us by our own actions and the actions of surrounding things. But what are these relations? They can be nothing more than certain secondary states of consciousness, arising through connexions of the primary states. Unable as we are to transcend consciousness, we can know a relation only as some modification of consciousness. The original modifications of consciousness are the feelings aroused in us by subjective and objective activities; and any further modifications of consciousness must be such as result from combinations of

these original ones. In all their various kinds and compounds, what we call relations can be to us nothing more

than the modes in which we are affected by bringing together sensations, or remembered sensations, or both. Hence what we have next to do is, first to resolve the special kinds of relations into more general kinds, ending with the primordial kinds; and then to ascertain what are the ultimate phenomena of consciousness which these primordial kinds express.

CHAPTER XIX.

THE RELATIONS OF SIMILARITY AND DISSIMILARITY.

$357. Of all relations the most complex is that of Similarity—that in virtue of which we range together objects of the same species, notwithstanding their differences of magnitude, and in virtue of which we group under the same head, phenomena of causation that are widely contrasted in degree. Already, in treating of Reasoning and of Classification, much has been said of this relation which forms their common basis. Here it needs only to state what it is when considered under its most general aspect.

The similarity which we predicate of natural objects belonging to the same species, is made up of many component similarities. Two horses unlike in size, are similar not only as wholes, but are also similar in their parts. The head of one is similar to the head of the other; the leg to the leg; the hoof to the hoof; the eye to the eye. Even the parts of the parts will be found more or less similar; as, on comparing two corresponding teeth, the crown to the crown, and the fangs to the fangs. Nay, such minute components as the hairs show in their structures this same parallelism. One of these ordinary similarities, therefore, consisting of an intricate plexus of similarities held together in similar ways, and resolvable as it consequently is into simple similarities, will, by implication, be analyzed in analyzing one of these simple similarities.

Though similarities of sequences do not admit of a complication parallel to that which similarities of coexistences admit of, yet they admit of another species of complication; namely, that arising from composition of causes and composition of effects. There are similarities of simple sequences and similarities of complex sequences. By the gravitation of a weight, the string to which the weight hangs may be elongated, and there may be no other appreciable results; while by the joint action of a certain temperature, a certain amount of moisture, and a certain miasm, upon an individual of a particular diathesis, who happens to be in a particular state, there may be produced the immense complication of effects constituting a disease. Each of these sequences is classed with others which we call similar; and in conjunction with them may form a premiss for future conclusions. And though, in the first case, we have a single antecedent and a single consequent, while, in the second case, we have a group of antecedents and a group of consequents-though in this second case the antecedent is not a force but a variety of forces united in a special plexus of relations, and the consequent is not an effect but a variety of effects united in a special plexus of relations; yet, we so obviously think of a composite cause and a composite effect, as related in the same way that a simple cause and a simple effect are related, that in treating of similar sequences we may confine our attention to the simple ones, as those out of which the others arise by complication of the terms.

Thus, then, choosing some primitive type of each, we have to consider what there is in common between similar coexistences and similar sequences.

§ 358. Of the one class, similar triangles furnish the most convenient example; and as an example of the other, we may take the uniform sequence of heat upon compression.

It is needless to do more than remind the reader, that in both of these cases the similarity resolves itself into