Among the bodies in our environment that are ponderable and have mass the animate beings are so strikingly distinguished from the inanimate that in most cases we have not the slightest doubt whether a body belongs to the one kind or to the other, even if in some cases we happen not to be familiar with its peculiar form. In the first place, therefore, we must answer the question in a general way and tell what the distinguishing peculiarities are that mark them off one from the other.

The first peculiarity is this, that living organisms are not stable but stationary forms. This distinction is based upon the fact that a stable form is at rest or unchangeable in all its parts, while a stationary body, though it seems unchangeable in its form, internally undergoes a constant change of its parts. Thus, a brass faucet is a stable body, since it not only preserves its form and function permanently, but consists at all times of the same material and shows the same peculiarities, such as stains, defects in form, etc. It cannot be said, it is true, that it will remain completely unchanged for all time. Its metal suffers a gradual chemical and mechanical deterioration. But this is not essential to the existence of the faucet, since the deterioration varies greatly with circumstances, and if conditions are ideal it can be reduced to zero.

On the other hand, the jet of water flowing from the faucet is a stationary body. In favorable circumstances it can assume a constant form, so that at a hasty glance it might be taken for a stable glass rod. On closer examination it will be found that the parts of water of which it is formed are not the same at any given instant as the instant before, each part that has flowed away being replaced by another just as large following it.

From this difference in the nature of the two bodies results a difference in their behavior. If I make a mark on the faucet with a file, the mark remains permanent. But even if I sever the entire water jet with a knife, the cut is healed the next moment, because by reason of the continuous flow of the water, the severed place is instantly eliminated from the body. Owing to this nature peculiar to stationary bodies, they have the capacity of being healed or of regeneration.

For a body to continue permanently in a stationary condition the material of which it is composed must be permanently supplied. If we turn off the faucet, the water jet immediately disappears or "dies." Evidently, therefore, a stationary body can subsist by its own means only if it has the property or capacity to provide itself continually with the necessary material. This material consists in the main of ponderable or chemical substances of definite physical and chemical properties, and thus the change of substance, metabolism, appears as a necessary property of the stationary body. In order, however, that metabolism should take place we must have free energy, or energy having the capacity to work, since it is only free energy that can cause substances to change, just as every phenomenon in the world implies the equalization of free energy. For a stationary body to exist independently, therefore, it must have the property of being able spontaneously to possess itself of the necessary substances and of free energy. But since, as we have already said, the energy of organisms is stored up and used in the main in the form of chemical energy, the two tasks which a stationary body has to perform, that of meeting the need for substances and for energy, are as a rule externally combined. In organisms these two necessities combined are called nutrition, and thus we recognize in the capacity for self-acquisition of nutrition another essential property of organisms.

A third essential property of organisms is the capacity for reproduction, for the bringing forth of similar beings. It is never impossible that the balance between the receipts and expenditures of a stationary body should, in consequence of some external causes, be disturbed, even when under normal conditions it possesses the property of self-nutrition. If the disturbance remains below a certain point, then, as we have already stated, regeneration sets in. But the disturbance may rise above that point, in which case the body ceases to exist, or dies. Then a similar body will not arise unless the manifold necessities that have led to the origin of the first will combine again to produce the second. That such a thing is possible, that, in fact, it often happens, is shown, for example, by the waves of the ocean, which have a stationary character since, while they are composed of constantly changing masses of water, their form remains unchanged. The waves are destroyed in the breakers, but arise again and again through the action of the wind upon the surface of the water. But the more complex such bodies are the less easily they are formed, while once they have been formed and have found the conditions of their existence, their preservation is much easier.

Beings, therefore, which have the capacity to form similar bodies out of themselves regularly and at the right time can preserve their species much more easily than those in which this property is absent. Death has to a great extent lost its power over beings capable of reproduction. By way of illustration let us take another stationary thing, a flame. A flame is not an organism because it is not self-sustaining. Yet it multiplies itself. And while a single little flame soon dies out, the sea of flame of a burning forest, which started from a single small flame, is well-nigh inextinguishable, and it cannot be fought in any other way than by letting it die its natural death and burn to the end.

Thus, while the fulfilment of the first two conditions, the stationary change and the self-supply of food, could produce bodies, which would be able to exist for a longer or shorter period, but which at some time would have to give way to other bodies of different form and nature, the capacity for reproduction creates the condition that forms of the same species continue to exist even after the existence of the individual has ceased.

These three properties constitute the essential characteristics of animate things or organisms.

That the organisms are all constructed upon the basis of chemical energy is a fact of experience which may be understood to imply that the other forms of energy are not capable of producing the above-mentioned conditions. This is due to the properties of chemical energy to which I have already called attention: its great concentration and, at the same time, its capacity for prolonged preservation. That chemical energy is the only form of energy suitable to life is obvious from the fact that in airship navigation, for example, the kinetic energy required for steering can be supplied only in the form of gasoline or hydrogen, that is, in the form of chemical energy, because any of the other forms would be much too heavy. The flight of a bee or the swimming of a dolphin cannot be conceived of except as brought about through chemical energy.

That this chemical energy is essentially that of carbon has also been established by experience, although it is not quite universal, for the sulphur bacteria found their household upon the energy of sulphur. The cause of the preference of carbon is again to be sought in its special fitness for the purpose, due, on the one hand, to its wide distribution, and, on the other hand, to the exceeding manifoldness of its combinations.

Finally, the construction of the organisms from a peculiar combination of solid and liquid substances can be proved to be equally due to technical relations.

These three last-named peculiarities are therefore to be regarded as the special characteristics of the organisms with which we are acquainted on the surface of the earth in the conditions there prevailing. We need not regard them conceptually as unchangeable or irreplaceable. But the first three characteristics, namely, the stationary nature, self-supply of nutrition, and reproduction, we may regard as the essential characteristics of organisms. They constitute the frame within which everything must be found which we should recognize as living in the widest sense.

55. The Storehouse of Free Energy.

If we ask whence the organisms obtain the free energy which they require for the maintenance of their stationary existence, the answer is that solar radiation alone furnishes this supply. Without this permanent supply the free energies upon the earth, so far as our knowledge goes, would long ago have reached a state of equilibrium, and the earth's bodies would be stable, that is, dead and not stationary and living.

It is comprehensible, therefore, that machines should have evolved in the organism for transforming the radiant energy of the sun into a permanent form, and, as we have already learned, chemical energy is permanent, while radiant energy is an extremely transitory form of energy, that is, it changes very readily. The very fact that, owing to the change from day to night, the supply of radiant energy periodically ceases, makes the storing-up of energy for the night necessary to the existence of a form dependent upon it. Thus, we recognize in the photochemical processes, that is, in the transformation of radiant energy into chemical energy, the foundation of life on earth.

This work is done by the plants, which thus provide a store of free energy not only for their own needs but also for all the other organisms which possess themselves directly or indirectly of the plant-chemical supplies in order to utilize them for their individual purposes. In this manner nourishment in the widest sense is secured for all organisms, being based upon the regular supply of free energy derived from the sun. This also explains the great chemical similarity of all organisms, which could not subsist if they were not so constructed as to be able to utilize the chemical energy in the form in which it is provided by the plants.

Of the great stream of free energy poured out from the sun into cosmic space the earth receives an extremely small portion (corresponding to the bit of space it occupies in the heavenly sphere as seen from the sun), and the plants collect and store up only a very small fraction of this portion received by the earth. Measurements have shown that in most favorable circumstances a plant leaf changes only about 1/50 of the radiant energy it receives into chemical energy. If we consider that only a small part of the surface of the earth is covered with plants and that during the winter no energy from the sun is stored up at all, we perceive what infinite possibilities for development there still are in arresting and storing up free energy. The part stored up by the plants flows from these into the countless streams, brooks, and veins of the other organisms, to end finally as used-up energy, or energy at rest. This energy is at rest, it is true, only in relation to the earth's surface. We do not know whether the radiation from the earth, which at present amounts to about as much as the radiation from the sun to the earth, is in its turn somewhere utilized.

While the free energy is poured out in such a stream in one direction, the ponderable substances of which the organisms are made up circulate through plants and animals and back again. This is especially true of carbon, which is freed from its combination with oxygen, that is, from carbonic acid, by the sun energy transformed in the plants. While carbon serves to build up the plant body and represents its supply of chemical energy, the oxygen is returned to the air. These two substances are again chemically combined in the various organisms and the quantities of energy which were necessary for their decomposition are again available for the manifold functions of life. The product of the chemical combination, carbonic acid, returns to the air and is ready for renewed decomposition in the plants.

Thus, the entire mechanism of life can be compared to a water-wheel. The free energy corresponds to the water, which must flow in one direction through the wheel in order to provide it with the necessary amount of work. The chemical elements of the organisms correspond to the wheel, which constantly turns in a circle as it transfers the energy of the falling water to the individual parts of the machine.

56. The Soul.

Our observations so far have shown the organisms to be extremely specialized individual instances of physico-chemical machines. Now we have to take into consideration a property which seems markedly to distinguish them from the lifeless machines, and which we have already encountered in the very beginning of our treatise.

It is the property which we there called memory, and which we will define in a very general way as the quality by virtue of which the repetition in organisms of a process which has taken place a number of times is preferred to new processes, because it originates more easily and proceeds more smoothly. It is readily apparent that by this property the organisms are enabled to travel on the sea of physical possibilities as if equipped with a keel, by which the voyage is made stable and the keeping of the course is assured.

If we ask whether this is exclusively a quality of organisms the question cannot be answered affirmatively. Inanimate bodies also have something like the quality of adaptation. An accurate clock attains its valuable qualities only after it has been going for some time, and the best violin is "raw" until it has been "broken in." An accumulator must be "formed" before it can do its normal amount of work. All these processes are due to the fact that the repetition of the same process improves the action, that is, it facilitates or increases it.

Adaptation or memory, then, is not limited to organisms. In inanimate things, however, this property is comparatively rare. Memory, therefore, is to be regarded as another property of organisms representing an extreme specialization of the inorganic possibilities. This is an important point of view for what follows.

In the first place, this property of adaptation facilitates and assures nourishment. If we take the fundamental idea developed by Darwin, that that predominates in the world which by virtue of its properties endures the longest time, then it is evident that a body which teleologically preserves and elaborates its nourishment will live longer than a similar body without this property. Moreover, by the general process of adaptation, these "teleological" properties come to be more greatly developed and more readily exercised in the body that lives longer, so that its long life gives it another advantage over its rival. Thus we can understand how this property of adaptation, which at first is to be conceived of as a purely physico-chemical quality is found developed in all organisms.

In its most primitive forms the quality of adaptation gives rise to the phenomena of reaction, or to reflex actions, that is, to a series of processes in the organism in response to the stimulus of an outward energy. This response is made in furtherance of the life of the organism. Reactions that serve a certain end, that is, teleological reactions, can naturally be developed to such stimuli alone to which the organism is frequently and regularly subjected. This is why adaptation to unusual phenomena is generally lacking, and in relation to them the organisms are often extremely unfit. The typical example of this is the moth, which flies into the light and is burned.

As the reactions become more fixed they develop into longer and more complicated series, which then appear to us as instinctive actions. But here, too, we find the characteristic unsuitability when unwonted circumstances arise, even if the teleologic reactions to stimuli become more manifold.

Finally, there are the conscious acts which appear to us to be the highest degree of the series. It is with the teleologic regulation of these conscious acts, including the very highest activities of mankind, that this book deals. They are distinguished from instinctive action by the fact that they no longer proceed in a single and definite series, but are combined at need in the most manifold ways. But the fundamental fact, namely, that actions are based upon the repetition of coinciding experiences, at once appears here also, since the basis of the entire conscious life of the soul, the formation of concepts, is made possible only through repetition. Thus, we are justified in regarding the various degrees of mental activity from the simplest reflex manifestation to the highest mental act as a connected series of increasingly manifold and purposive actions proceeding from the same physico-chemical and physiological foundation.

For good reasons it is generally assumed that the organisms have not always been what they are now, but have "developed" from previous simpler forms. It is undecided whether originally there were one or several forms from which the present forms sprang, nor is it known how life first made its appearance on earth. So long as the various assumptions with regard to this question have not led to decisive, actually demonstrable differences in the results, a discussion of it is fruitless, and therefore unscientific. The usual word evolution is non-purposive in so far as it signifies the appearance of something already existing. Another conception is better according to which the influence of changed conditions of existence has yielded the most important factor of change.

The change that the organisms undergo is always in a definite direction. More and more complex and manifold forms are evolved, and the evolution of these forms is characterized by an ever greater specialization of the functions of life, so that every specially developed organ comes to perform but one function. It is true that by this means the organism is better fitted to perform those functions, but at the same time it grows more susceptible to injury, since its existence depends upon the proper simultaneous activity of many different organs. Such an evolution, therefore, can occur only when the general conditions of life have grown steadier, so that the danger of disturbance becomes less. We are accustomed to regard changes in this direction as higher developments, and the progressive simplifications of the organization (as for example in parasites) as backward steps.

Since our opinion as to what constitutes a higher and a lower organism is doubtless arbitrary, let us ask whether it is not possible to find an objective standard by which to measure the relative perfection of the different organisms. The question must be answered in the affirmative when we take into consideration the following. Since the quantity of available free energy upon the earth is limited, the organism which transforms the energy at its disposal more completely and with the least loss into the forms of energy necessary for the function of life, must be regarded as the more perfect organism. In fact, we observe that with increasing complexity of the organisms there is for the most part also an increasing improvement in that direction, and we can therefore speak of some beings as more perfect than others. This view-point is especially significant in the evaluation of human progress, appearing, as it does, as the general standard of all civilization.

The perfection of the organism shows itself in relation to the outer world in the development of the sense organs. While a single-celled animal reacts almost exclusively to chemical, sometimes also to optical, stimuli, and receives these with the entire surface of its body, special parts of the body develop more and more toward perfection. These are the parts that respond with special ease to the appropriate stimuli, that is, react to them with an increasingly smaller expenditure of energy. Then the points at which the stimuli are received are separated from those in which the reaction occurs, and the two are connected by conducting paths, the nerves, in which an energy process takes place. Our present knowledge of this process still leaves much to be desired. It is a process which moves with fairly great but by no means extraordinary rapidity (about ten to thirty meters per second) along the conducting paths. At the one end of this path it is caused by actions of various kinds, chiefly that of the specific energy, for which the sense organ is developed. At the other end it discharges specific effects. There is no doubt that here we have in each instance a case of energy transformation connected with a discharge, that is, with the action of other energies which lie at the ends ready for change. Hence there is no equivalence between the different kinds of energy, the discharging and the discharged, mostly not even a proportional relation, although both increase and decrease simultaneously.

What the form of the energy is that is propagated in the nerves is unknown. It can be either a special form which arises only under the conditions here present (just as, for example, a galvanic stream develops only under definite chemical and spacial conditions), or a special combination of known energies, as in sound and probably in light. Some day, it is likely, we shall have a more accurate knowledge of the nerve process which will solve the question.

When such a process is caused by some energy impulse from without, it may produce various results. In the simplest case it discharges the corresponding reaction, just as the leaves of the sensitive plant close when they are touched. Or it may give rise to a series of processes following one another like the instinctive actions. Or, finally, it may bring about a series of inner processes which lead to an extreme differentiation of slight differences of this stimulus and to a corresponding graded reaction with the anticipation of success. We call this conscious thinking, willing, and acting.

Through the age-long effect of the blunder committed by Plato in making a fundamental distinction between mental life and physical life, we experience the utmost difficulty in habituating ourselves to the thought of the regular connection between the simplest physiological and the highest intellectual acts. Moreover, this contrast has been accentuated by the mechanical hypothesis. If we abandon the mechanical hypothesis and adhere to the summarization of experience free from all hypotheses, as represented in the science of energy, this contrast disappears. For even if we concede the impossibility of conceiving thought as mechanical, there is no difficulty in conceiving of it as energetic, especially since we know that mental work is connected with expenditure of energy and exhaustion just as physical work is. However, the elucidation of this subject lies almost entirely in the future since the idea just developed has but only begun to influence scientific work in this field. But judging from the results that have already been obtained we may hope for a speedy development.

58. Society.

The external circumstance that as an organism multiplies the new being must come to life in the proximity of the older one, is in itself cause for the formation of closed groups confined to certain localities by animal organisms of the same species. But they become scattered if the advantage of their living together is not such as to outweigh the disadvantage of having a narrow field of competition for the means of sustenance. Thus we see different plants and animals behaving differently in this respect. While some species live in as great isolation as possible, others form communities, even if there is no mechanical tie to hold them together by a common integument.

Since the second case is true of man in a highly marked degree, his social characteristics and needs form a large and important part of his life. And since, further, the socialization of man makes continuous headway with increasing civilization—we need but think of the development of the former little groups and tribes into states and the present very active internationalization of the most important affairs of mankind, especially of the sciences— the social problems also occupy an ever larger place in the organization of human life.

What distinguishes man most essentially from the other animals, even the most advanced, is his capacity for perfection, which in the lower animal can be paralleled at best by its capacity for self-preservation. While the organization of the animals within the short period of which we have any historical knowledge has to all appearances remained essentially unchanged, the world of mankind has changed in quite a remarkable way. This change consists in an increasing subjection of the external world to human purposes, and rests upon the increasing socialization of his capacities.

Memory and heredity (the latter being but an extension of memory to the offspring, which is to be conceived of as a part of the older organism) secures in the first place only the preservation of the stock and the renewed development of the new individual in the average type. If a specially favored individual succeeds in accomplishing greater achievements, he may in favorable circumstances transmit this capacity for higher attainments to his offspring. But such individuals gain an advantage in the struggle for existence only if the other sides of their activity do not suffer curtailment as a result. With the limited amount of energy at the individual's disposal every extraordinary accomplishment involves a corresponding one-sidedness, and as soon as a certain measure is slightly overstepped, it will cause a reduction of the other functions which will render the individual less fit in the struggle for existence. But this is true only so long as an individual must live by himself. As soon as he forms part of a social organization which benefits by his particular activity, the organization compensates for the personal disadvantages by its collective activity, and a social community not only finds room for such special developments, but it even encourages and promotes them.

We have already seen that such manifestations occur within the organism itself. Higher functions, depending upon the higher susceptibility of the sense organs, can only be attained at the expense of the general functions by the organ in question. We observe this fact in all socially organized beings, like bees and ants, which display a high degree of specialization in the functions of the individual subordinate groups; the specialization often being carried so far that the individual groups can no longer subsist by themselves alone. It is only the organization as a whole that is capable of permanent existence.

While the evolution of such superior functions involves a corresponding differentiation, and therefore a division and separation of the superior functions within the social structure, the necessity for communication and for mutual support results in an approximation of the individuals and the groups. In every society, therefore, the centrifugal and the centripetal forces work simultaneously in co-operation and in opposition to one another. While the extreme specialization on the one hand seems to make for the best individual functioning, on the other hand it renders the entire collective structure much more dependent, and therefore much more subject to injury, as is shown by the example of the queen bee, whose departure threatens the existence of the entire hive. Thus a medium degree of differentiation will as a general rule produce the most permanent social structure.

59. Language and Intercourse.

The essential value of the social organization resides in the fact that the work of the individual, in so far as it is adapted to it, accrues to the benefit of the collective whole. For this it is absolutely essential that the members of the collectivity should be able to have intercourse with one another in order that every part of the general activity may be communicated to the others. This intercourse is obtained through language in the most general sense.

We have already learned that the essence of language consists in the co-ordination of concept to sign. The social application of language demands that the signs co-ordinated to the concepts in use should be the same for all the members of the social organization. Only in this way can the members make themselves mutually understood. But intelligible means of communication and division of labor impart to the social knowledge that is set down in writing a kind of independent existence. Many centuries ago the possibility ceased for one person to store in his memory the entire stock of human knowledge. Nowadays we have men who are versed only in single parts of separate sciences, and the aggregate knowledge appears at first to be a unity existing only in thought. But because this knowledge is set down in signs which endure far beyond the life of the individual and at the appropriate moment can unfold its entire power even after a long period of inactivity, it has acquired an existence of a social character independent of the individual. For although it survives the individual, it cannot survive the death of human society.

As the socialization of all mankind advances to ever greater unities, the linguistic limitations sprung from former stages of evolution prove to be a hindrance. The mother tongue, of course, forms the first and most important entry for the individual to the common store of knowledge. But in view of the linguistic limitation of which I have just spoken the efforts in our day are carried on with renewed zeal to create a universal auxiliary language (p. 100) by means of which intercourse should be made possible beyond the language boundaries. There have already been gratifying results.[I]

60. Civilization.

Everything which serves the social progress of mankind is appropriately called civilization or culture, and the objective characteristic of progress consists in improved methods for seizing and utilizing the raw energies of nature for human purposes. Thus it was a cultural act when a primitive man discovered that he could extend the radius of his muscle energy by taking a pole in his hand, and it was another cultural act when a primitive man discovered that by throwing a stone he could send his muscle energy a distance of many meters to the desired point. The effect of the knife, the spear, the arrow, and of all the other primitive implements can be called in each case a purposive transformation of energy. And at the other end of the scale of civilization the most abstract scientific discovery, by reason of its generalization and simplification, signifies a corresponding economy of energy for all the coming generations that may have anything to do with the matter. Thus, in fact, the concept of progress as here defined embraces the entire sweep of human endeavor for perfection, or the entire field of culture, and at the same time it shows the great scientific value of the concept of energy.

If we consider further that, according to the second fundamental principle, the free energy accessible to us can only decrease, but not increase, while the number of men whose existence depends directly on the consumption of a due amount of free energy is constantly on the increase, then we at once see the objective necessity of the development of civilization in that sense. His foresight puts man in a position to act culturally. But if we examine our present social order from this point of view, we realize with horror how barbarous it still is. Not only do murder and war destroy cultural values without substituting others in their place, not only do the countless conflicts which take place between the different nations and political organizations act anticulturally, but so do also the conflicts between the various social classes of one nation, for they destroy quantities of free energy which are thus withdrawn from the total of real cultural values. At present mankind is in a state of development in which progress depends much less upon the leadership of a few distinguished individuals than upon the collective labor of all workers. Proof of this is that it is coming to be more and more the fact that the great scientific discoveries are made simultaneously by a number of independent investigators—an indication that society creates in several places the individual conditions requisite for such discoveries. Thus we are living at a time when men are gradually approximating one another very closely in their natures, and when the social organization therefore demands and strives for as thorough an equalization as possible in the conditions of existence of all men.