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habit of mind, and a freedom from annoying cares. tions will be found to all general principles on this subject, as upon all others. Some men live to an advanced age when every. thing seems to threaten them with an early death; and others, when everything promises an extended existence, are disappointed in their expectation. It is particularly to be remembered, that life is not to be prolonged by deferring the adoption of the necessary means till old age is already approaching. The causes which determine the period of our dissolution may be at work while we are in the midst of health and indulgence; and may be determined, so far as it depends upon natural causes, even in youth or infancy. No doubt where the capital of life has been prematurely expended, excessive care, and a rigid husbanding of what is left, may do somethimg toward a prolongation of our years. Lewis Cornaro, who from fast living was thought ready to die at the age of thirty-five, by adopting a strict and self-denying regimen, lived beyond a century. But it is not wise in matters of importance to be governed by exceptions; and it will be found in respect to health, as well as in our worldly affairs, that it is safer to practise an early economy than a late parsimony, if we would live comfortably in the one case, or long in the other.

CHAPTER XVII. (W.)

ON INSTINCT AND INTELLIGENCE, AND ON THE MENTAL CONSTITUTION OF ANIMALS.

THE individuality of everything possessed of life, and the absence of this individuality in everything not possessed of life, were mentioned in the Introduction as among the characteristics by which organic, organized, or living matter is distinguished from inorganic, unorganized, or common matter. This difference is an important circumstance in its relation to the laws by which these two divisions of existing things are governed. The whole universe of inorganic matter, as it respects these laws, constitutes a single system. On the other hand, each distinct plant and

animal, however humble, also constitutes in itself a single system. There is one principle, which, by one uniform set of laws, governs the inorganic material universe as an integral whole. Each living thing is also an integral whole, governed by its own principle, and acting by a set of laws peculiar, in a certain sense, to itself. The gravity which makes a stone fall or a balloon ascend, is the same as that which regulates the motion of a planet in its orbit. The life of the insect has no such community of existence with the life of the man. Every living thing is insulated from every other living thing. The forces by which the operations of any one living system are carried on, have no interchangeable relations with those by which the operations of any other are carried on. Each organism is a unit, in regard to the laws which govern it. Each is shut up in its own individuality. So far as its life is concerned, it can impart nothing, it can receive nothing. itself, and for itself, its own power and its own cause.

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This is a remarkable condition of existence. Our own reflections teach us that it is a real one, so far as our conscious powers are concerned; for what can be conceived of as more insulated than the consciousness of each and every man? But it is equally real with regard to every the minutest detail of his structure and his functions. Of this there is a homely, but convincing, illustration in the fact, that even in so slight a matter as the odor of the skin, which is dependent upon an emanation the pecularities of whose composition no chemistry can detect, there are no two individuals so precisely alike that the senses of the dog cannot distinguish one from the other.

The whole universe of inorganic matter, then, constitutes an individual economy, governed by laws, and possessed of powers, which pervade, and are common to, every part of it. Each separate living organism is also an individual economy, governed by laws, and possessed of powers, which pervade, and are common 'o, every part of its organization, but extend to nothing beyond it. Both in the universe of inorganic matter and in living organisms the economy is directed by an intelligent principle. In the former this is a general one; in the latter it is peculiar to each individual. Among the possessors of life there is a wide difference in the extent and variety of the powers which are

exercised; yet they nevertheless always retain this essential characteristic of an insulated individuality. Thus in all plants, and perhaps in some animals, although operations directed by an individual, intelligent power are constantly carried on, there is no sensation, no perception of an external world, and no consciousness of existence; whilst in a large proportion of animals, perhaps in all, each of these is present. Probably in the lower forms of animal life, sensation, perception, and consciousness are dim and indistinct when compared with the intense character which they exhibit in the higher forms; still they exist. But, what is particularly to be observed in connection with the present subject is, that even in these higher animals, beside the performance of operations under the cognizance of sensation, perception, and consciousness, there are also performed other operations, essentially the same with those of plants, of which they take no cognizance, and over which they have no personal control, and yet these operations, like those in plants, are under the direction and superintendence of an individual and intelligent, though still unconscious, principle.

In ourselves, for example, the functions of sensation and motion report themselves to our consciousness; we recognize the organs by which they are performed, and the results they bring about. It is not so with those functions by which the body is nourished and the organs are kept in repair. We do not notice their performance at all, except indirectly; and we do not even recognize the existence of the organs by which they are carried on. Now these functions are essentially the same as those of the plant; and, like those of the plant, they may be perfectly performed without being perceived by the consciousness of the organic being in which they are exercised. We have then, in a limited sense, two principles of intelligent life. Of one of these we are conscious, and its operations are under the influence of the will; whilst of the other we are not conscious, and its operations are entirely independent of the will. Still these principles have not that distinctness from each other which this statement might seem to imply. They have intimate reciprocal relations, a common bond of union; they are indissolubly bound together by a necessary condition of their existence; they constitute a

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Under certain abnormal conditions, we perceive the ence and actions of the organs of the vegetable life within us ; whilst, on the other hand, these organs are powerfully influenced by the passions and emotions of our conscious, or animal, life.

From the unconscious, but still intelligent, principle proceed those actions, or operations, which are called Instinctive; from the other principle, the conscious, proceed those actions which are called Intelligent. It is to be observed, however, of many of the latter, that, although they are carried on by the aid of the senses and the voluntary muscles, under the full cognizance of the animal, yet the impulse from which they proceed, and the skill with which they are directed, are entirely out of the sphere of consciousness, and are to be referred to the same source as the functions of organic life.

We may distinguish, then, three classes of operations by which the economy of animals is carried on.

First, Those which are prompted, devised, directed, and executed by the unconscious principle;

Secondly, Those which are prompted, devised, and directed by the unconscious principle, but are executed by the organs of the conscious principle, that is, by the organs of sense and motion, and are often suggested by information derived from these; and Thirdly, Those which are devised, directed, and executed mainly by the intelligence of the conscious principle.

Of these last operations, however, many are prompted by suggestions from the unconscious life, and are often executed by means not to be distinguished from those by which that life is administered. So, also, voluntary actions which have become habitual are not easily to be discriminated in their mode of performance from those which are instinctive, and, on the other hand, purely instinctive actions resemble closely those which are the result of habit. The artisan who devotes his life to the practice of some very nice and complicated workmanship, and the musician who executes on a piano-forte two or three parts of a complicated harmony, are not anapt representations of the bee or the wasp, going through with their tasks, adapting themselves to circumstances that may arise, and devising, within certain limits, means to obviate occasional difficulties with equal skill.

There is such a combination of these two principles of activity in most of the operations of the life of animals, especially of the higher, that it becomes extremely difficult to analyze their character and to determine from which they proceed. Even in man, where instinct has the least, and intelligence the most, influence upon these operations, it will be found that the former takes a larger part in them than we are apt to imagine, though still a part subservient to, and directed to, the purposes of the latter. Thus, in voluntary motion, there is no muscle of the body which we can cause to contract by a simple act of the will, directed to it with this specific purpose. We will the hand to grasp an object, and are sensible of the consequent effort in the hand, but of none in the muscles that move the hand; for these are situated at some distance, and, unless instructed by a knowledge of anatomy, we have no idea where. We will to hold our breath; but this we do, not by willing the cessation of the action of the muscles by which respiration is performed, but by interposing a mechanical obstacle to the entrance of air, by an effort directed to quite a remote part, the aperture of the windpipe.

It is also true of some of those higher operations which appear most exclusively in the domain of the intellect, that in the instruments and mode of their performance the instinctive or unconscious element enters largely. Thus, in operations which relate to numbers, although the intellect is wholly concerned in the conception of the object of the process and the general course of procedure, the subordinate steps of the process are performed instinctively. This is so much the case, that those individuals in whom the capacity for numerical calculation is carried to excess as part of their original constitution, Zerah Colburn for instance, are incapable of explaining the steps by which their results are arrived at; they are reached by a species of instinct. So, too, the education of the senses and of the voluntary muscles in infancy is carried on by a species of instinct, rather than by a voluntary process set on foot by the conscious intelligence, with this definite purpose in view. The same is true of the original acquisition of language. The original tendency, and the first steps taken, are properly instinctive, though the voluntary and intelligent principle begins sooner or later to take charge of