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satisfactory that the discovery is realized. Hence the remark, 'he discovers that proves.' Honour belongs to the first suggestion of a discovery, if that suggestion was the means of setting some one to work to verify it, but the world must ever look upon this last operation as the crowning exploit.

The homologies of the skeleton imply a wide range of similarities hunted out through the thickest concealment of diversity. The identity of structure of all animals of the vertebrate class,-mammalia, birds, reptiles, and fishes; the correspondence of the upper arm of the man, the foreleg of the quadruped, the wing of the bird, and the anterior fin of the fish, —implies a very great insight into structure, and a power of setting aside first appearances. The similarity of the segments of the same skeleton, from the crown of the head to the tip of the tail, constitutes the serial homology, which is the working out of Oken's discovery on the skull of the deer. The discovery of these homologies represents the struggles of the human intellect with the perplexity of the world. In the explanation of nature, first thoughts are scarcely ever correct. The superficial resemblances bring together things that have no deep community of structure, and hence no knowledge is derived from one to another. The comparison of a salmon with a seal can only mislead; the comparison of a seal with a whale may improve our knowledge of both. When a superficial likeness in two objects,-a sameness in some one prominent feature,—is the sign of a deep likeness, or a sameness in many other features all of great importance, we can apply the whole of the knowledge we have obtained of the first to the second; that is, by studying one we are master of the two, and thus economize our labour. If I find out that a bat is not a bird, but one of the mammalia, I instantly transfer to it all that I know of the common characters of the mammalia: but if I identify a bat with an owl I gain nothing, for the likeness between the two is superficial or isolated, it does not imply a number of other likenesses, and the comparison is therefore unprofitable. The progress of real discovery consists in seizing these pervading resemblances, and passing by the others. It is a singular fact that where there

is the greatest amount of real sameness, there is often the least apparent sameness; which doubtless only shows that the vulgar eye is satisfied with a very narrow and limited glance at things. The kindred features of a family may not be what gives the individual its popular interest.

PHENOMENA OF SUCCESSION.

29. The successions that make up the flow of changes and events in the world are a subject of study rising above the still life aggregates that we have been just considering. Even in those aggregates we have not absolutely refrained from implying phenomena of succession, as, for example, when we spoke of the experimental properties of bodies; whence it will be apparent that to deal with the world as we find it, aggregation and succession must both enter into our field of observation.

Under Contiguity we have classified and illustrated the different kinds of succession prevailing around us. Some are Cyclic or periodic, as day and night, the seasons, the heavenly appearances generally; the tides, the winds, the revolution of machinery, the routine of life. Others are successions of Evolution, as in the growth of living beings, and the constructions of human industry. Some are characterized by effect, or the production of some telling sensation, or sudden change, as in a blow, an explosion, a burst of music, a dramatic scene. Apart from these popular and salient effects, we have the links of succession laid hold of in the Scientific view of cause and effect. Lastly, Human History at large is a grand ensemble of succession, which no one mind can totally comprehend, and which consequently presents itself in innumerable aspects to the intellects of men.

Among all these various kinds of succession, identifications are struck through the medium of similarity. Hence arises classes of succession that may substitute another in practice, and that throw light upon one another as regards our knowledge. To take a familiar example from the group of Evolutions, Each person has a familiar knowledge of

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the growth of their own frame, and, by identifying self with other beings, can transfer all this knowledge to them, thereby inheriting an insight far beyond the field of actual inspection.

The identifications that have been traced among these innumerable varieties of sequence, and which remain held together, by the use of language, as the common estate of civilized men, have vastly enlarged the sum of human knowledge and the compass of human power, besides yielding much refined gratification. To do them full justice, however, we must specify two great divisions that they fall under, namely, the Real and the Illustrative; the one implying an identity in the actual subject or intrinsic quality of the sequence, the other implying a sameness in some mode or aspect of it. Of the first class are the scientific and practical identities; the second are those that serve as a medium of intellectual comprehension or of artistic adornment. When we term certain atmospheric movements aerial tides, thereby identifying them with the tides of the ocean, the comparison is strict and scientific, for both phenomena are caused by one and the same natural power, namely, gravitation; but when we speak of a tide in the affairs of men,' the identity is not real, but merely illustrative through a certain similarity of phase or aspect; the ebb and flow of human prosperity has no dependence upon gravitation, it grows out of quite another class of natural impulses. Owing to the fact that the same effect may be produced by a plurality of causes, there are practical identifications among forces in themselves distinct, as when in quarrying we substitute the expansive action of moisture on dry chips of wood for the explosion of gunpowder. The sources of power in these two effects are not the same; they do not fall under a common natural cause. Nevertheless, this, too, would be called a real, and not an illustrative identity; it would be fructifera, and not lucifera, or poetica.

30. The illustrative comparisons, however, are not confined to phenomena of succession; they occur equally among the objects brought in under the previous head, namely,

aggregates, conjunctions, or appearances of still life. On this account I prefer to treat 'illustration' as a separate subject, and under the present head, 'successions,' I shall merely cite a few examples of the identification of likenesses considered as real, or believed to be real. And to commence with sequences that are periodic or cyclic:-the revolutions of the year are too much alike to present a case of difficult identification, on which alone any interest hinges. In the rising and setting of the stars there is one point of similarity that might for a long time escape observation, in consequence of accompanying dissimilarities, namely, that in the same place the stars all rise constantly at the same angle, the angle being the co-latitude of the place; at latitude 60° the angle is 30°, at latitude 50° it is 40°. Now there are two disguising differences in the rising and setting of the various stars; one relating to the height they reach when at their highest, and the other relating to their time of rising, which last element differs for the same star throughout the year. It takes a steady glance, a ready appreciation of mathematical elements (such as this of the angle of rising), and a considerable reach of the identifying faculty to make out for the first time a common feature of this description in the midst of a dazzling and variegated scene. An absence of poetic feeling would be almost an indispensable requisite.

In the vegetable kingdom, as seen in temperate and cold countries, men soon attain to the generalization of alternating life and death, in the cycle of the year. Notwithstanding the boundless variety and diversity of vegetable nature, this fact, of summer growth and autumnal fading, is too prominent to be disguised by the distinctions between a garden flower and a forest oak. It would consequently be one of the earliest generalizations of the human race living out of the tropics. The same remark would apply to the alternation of waking and sleeping, as a fact of animal life in general. The identification of the daily repose of men and animals with the hybernation of reptiles and some other classes, would be somewhat less obvious, but by no means difficult to observant men; unless indeed an artificial obstruction were created by a comparison with death, or with the winter of vegetation, having already

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got possession of men's minds. We have repeatedly had occasion for this remark, as to the influence of prepossessions in stifling a stroke of identity, and the present is only a fair supposition of that nature.

The steps of the generalization of the planets, or the tracing of a common character in spite of accompanying dissimilarity among these wandering bodies, would be interesting to follow if we could now recover them. The discovery of the common fact of their circling round the entire heavens was by no means easy in the case of the inferior planets, Mercury and Venus, seeing that men's minds would in their case be carried away with the more limited circumstances of their attending on the sun, and appearing as morning and evening

stars.

The

The successions of evolution are typified and principally constituted by the growth of living beings. Each plant and animal, in the course of its existence, presents a series of phases, and these we may watch more or less closely, so as the better to know the course of the evolution. With the fact of birth and death, as a property of all living beings, we become acquainted through the identifying operation which seizes hold of this common feature in the midst of never so much variety in all else that can constitute a living being. But identities of the special mode of growth can be traced among limited groups, which are thereupon formed into classes; as in animals, the oviparous and viviparous. successions of insect life are peculiar and interesting, and, as regards the distinct stages and states of existence, the identifications through the animal tribes are curious and instructive. Close observation of individuals is necessary to put the mind in a position to strike out such identities; the absence of vulgar wonderment, poetic illusion, and strong prepossessions in favour of some mistaken comparison is also very helpful. The physiological department called Embryology, includes the knowledge of the early evolution of animals, and it is very much dependent upon identifying the modes of growth of creatures considerably different from one another, as the chicken with the infant. Here, however, there was no great