140. Thesis I. Living bodies cannot originate from nonliving bodies.
Proof. The effect cannot be superior to the cause; now, there is something in the vital principle superior to all the powers of non-living bodies, no matter how these be combined with one another; viz., it gives living bodies essences superior to the essences of all inorganic bodies. For the essences of things are known by observing their properties and operations; now, all living bodies are observed to have certain properties and operations most of which are superior to those found in any non-living bodies; therefore, all living bodies have natures or essences superior to those of non-living bodies.
The two classes differ:
1. In structure. All living bodies, and they alone, are furnished with organs -- i.e., with parts of peculiar structure suited to perform vital acts.
2. In figure. All living bodies have determined figures proper to each species, and these figures are bounded by curved lines; while non-living bodies have no determined figures, except crystals, and these are bounded by straight lines.
3. In growth. Living bodies begin with a cell, from the evolution or multiplication of which the whole organism gradually arises; this development proceeds by means of nutrition, or intussusception of food, which is transformed into the living substance. Non-living bodies do not arise from a cell; and they increase by juxtaposition of particles from without.
4. In origin. Living bodies never come but from germs produced by other living bodies; for the cells cannot be formed by mere chemical combinations, though all the simple elements be present in the proper proportions.
5. In chemical action. The vital principle of plants enables them to decompose carbonic acid into its simple elements of carbon and oxygen, absorbing the carbon by their leaves, thus overcoming its strong affinity for oxygen; while animals, inhaling oxygen, which so readily destroys dead matter, use it to support their animal life.
6. In unity. All the elements composing any plant or animal obey the vital principle which directs them to procure the preservation of the individual and of the species.
7. In duration. Living bodies have a limited period of existence, while nonliving ones are independent of time.
Objection. Fungi and maggots are generated by dead matter. Answer. They come from living germs floating in the air; the leading scientists are agreed that there is no spontaneous generation, but that, as nature is now, all living plants and animals come from living germs. As to the question whether the Creator could possibly establish spontaneous generation, see No. 158.
141. Thesis II. All plants differ essentially from all animals.
Proof. The essences of things are known by observing their properties and operations. Now, all plants are confined to these three functions: nutrition, growth, and reproduction; while all animals exhibit, in addition to these, the power of sensation, and, as a consequence of sensation, an appetite for sensible good, and a shrinking from sensible evil. There is, besides, in all animals an appropriate power of motion, which enables them to move instinctively upon the apprehension of good or evil. Therefore all plants differ essentially from all animals.
142. Objections: 1. Of some living things -- e.g., of sponges -- it is not certainly known whether they are plants or animals; therefore, the difference between them is but slight and cannot be essential. Answer. The difference between plants and animals is the power of sensation; though but slightly manifested, it constitutes an essential difference; so that if sponges possess it, as they seem to do, they are animals; if not, they are plants.
2. The sensitive plant has sensation, as its name indicates, and still it is not an animal. Answer. It has no sensation; its scientific name is "mimosa," because it mimics sensation; its leaves are mechanically contracted by outside influences, not by its own immanent action.
3. The sunflower turns its face to the sun, the tulip closes its petals at night, etc.; therefore they perceive the sun, the night, etc. Answer. The physical action of the sun and of the damp air upon those plants produces these mechanical effects.
4. But many plants grow towards the light, and growth is not mechanical action. Answer. The growth comes from the life-principle in the plant, but its effects are modified by favorable influences on the side of the light, and by unfavorable influences on the opposite side; this argues no power of sensation in the plant.
5. It cannot be proved either a priori or a posteriori that animals feel and plants do not. Answer. (a) It is known by the judgment of common sense. (b) It is proved scientifically by observing that all animals, even the lowest species which are certainly known to be animals, have organs of sense, while no plants, even the highest, possess these. Besides, animals have motions which cannot be explained except as consequent on the power of sensation, and they give signs, by cries, etc., of pleasure and pain, which no plants ever do.
143. Thesis III. All the vital acts of an animal flow from one vital principle.
Proof 1. Nutrition, growth, and reproduction in plants are not attributed to three distinct principles, but to one, the vegetative principle; because the effects are subordinated to one another, and thereby show a unity in the cause. Again, since all the functions of life in an animal are subordinate to one another, and co-operate harmoniously to one common end, there must be unity in the cause; i.e., there must be but one principle from which proceed all the vital acts of animals.
Proof 2. If the animal were composed of two vital principles, it would be two beings; for the vegetable would not be the animal, nor the animal the vegetable, but all men judge the animal to be one being endowed with vegetative action, yet not a vegetable.
144. Thesis IV. The vital principle in any living body is truly the form of the body.
Proof. The form of a body is that principle which makes it be such a body and not a body of another kind, which gives it such powers and actions and not other powers and actions; in a word, which constitutes the body in its species.
Now, such is the vital principle of any living body. For, 1. If the vital principle ceases to animate the matter, as it does in death, all the specific powers and actions of that body cease. 2. The mere matter, as separate from the vital principle, may become successively the food and the very substance of different plants and animals, its specific nature ever changing with the vital principles that successively inform it. But this supposes that the vital principle constitutes it in its species, or is its form.
145. Objection. The substantial form of a body is simple, and therefore indivisible; but the vital principle of some plants is divisible; e.g., a twig may be cut off and continue to live by its own life, the vital principle of the tree being divided. Answer. Simplicity has different meanings. We grant that all forms, as such, are simple; they are simple in two senses: 1. Inasmuch as they are not composed of matter and form; 2, inasmuch as they are not aggregates of parts quantitatively distinct, as bodies are. Just in the same senses is the vital principle simple, for it cannot be divided into matter and form, nor into parts quantitatively distinct. As to the curious question whether the principle of life is ever divided, we say that it exists whole and entire in the body and in every part of the body, so, however, that it can neither act, nor even exist, but in an extended body, excepting only the soul of man. To animate a body, the life principle requires a complete organism; therefore, when the organism is destroyed, the vital form ceases to be. Now, in many plants, and in a few of the lower animals, the organism is so simple and uniform throughout in its structure that, when divided, the several parts may still be suited to the functions of life. In such a case the principle of life may continue to animate the several parts; but it is not properly said to be divided; rather the body is divided; for the vital principle is whole and entire in both parts, which now become two plants. It was before whole and entire in all portions of one body; it is now whole and entire in all portions of two bodies, and in this sense it is rather said to be multiplied than divided; or, better still, it is neither; but the animal or plant is divided. (See upon "Simplicity," Inst. Phil. Nat., by Tilmann Pesch, S.J., No. 211. -- Compare St. Thomas's Summa, p. I, q. lxxvi., a. 8.) Thus the twig may become a distinct plant; thus, too, the segments of annulated worms, when severed from the rest of their bodies, become individual worms, this result being accomplished by the division of the matter and the multiplication, if you will, of the form. Other philosophers maintain that the principle of life is really divided in such cases; perhaps it is a mere dispute on words.
146. Theses V. and VI. The brute soul is irrational and therefore ceases to exist when the organism is destroyed.
Proof 1. It is a judgment of common sense that brutes are irrational or incapable of reasoning, and that their vital principles do not outlive their bodies.
Proof 2. I. That the brute soul is irrational is proved scientifically, (a) By induction. For it is found, by an endless variety of observations, that all the acts of brutes can be accounted for without supposing in them the power of reasoning, of drawing conclusions from premises; in other words, they give no signs of reasoning, and it would be unscientific to ascribe to them a faculty of which they give no indications. This becomes the more evident if we compare their actions with those of rational man. All men, in the full possession of their facu1ties, can grasp the abstract relation between means and ends, inventing and making new and various means, e.g., tools, to accomplish their designs; brute animals never do so; they can only follow the one beaten track to which their specific nature determines them. Hence, too, a man can improve himself by study, by exertions of his own talents; brutes cannot do this; they may be taught various actions by man, but they cannot improve themselves. Hence, too, a race of men may increase in knowledge and civilization; brutes act now as they were always known to act; and when, by the training of man or the change of physical surroundings, new ways of acting are brought about in some brute animals, it is found by experiment that all brutes of the same species would act in about the same way under those peculiar circumstances. Therefore the effects can be accounted for by reference to phantasms and organic modifications, without attributing to the brute the abstract perception of the relation between means and ends.
That brutes are irrational is proved scientifically, (b) From the nature of reasoning. Reasoning is absolutely impossible without universal concepts; for in all reasoning the middle term must be at least once distributed or taken universally. Now, brutes never give signs of having universal ideas: all their actions can be accounted for by means of sense-perceptions, phantasms, and instinctive action, which will be explained further on (No. 149).
II. The brute soul ceases to exist when the organism is destroyed. For it would be unwise to keep anything in existence which can answer no purpose; but the brute soul, when its organism is destroyed, can answer no purpose; therefore the Creator does not keep it in existence.
The minor is clear from the fact that all the functions of the brute soul -- i.e., nutition, growth, reproduction, sensation, and motion -- require bodily organs. Besides, it is an obvious principle that the nature of a being is of the same kind as its actions; now, the actions of the brute soul are all bound up in matter, therefore the brute soul is so too; and, therefore, it cannot exist without matter.
147. Some obvious corollaries follow from this: 1. That the brute soul, unlike the soul of man, cannot exist by itself; it is only the substantial form of the brute body. 2. That it needs no ceation to bring it into existence; it is educed out of the potentiality of matter, as are the forms of inorganic bodies; with this difference, that the brute soul, unlike those forms, is not educed from matter except by the action of a living agent of the same species.
148. Objections: 1. Many actions of brutes manifest design, the intelligent adaptation of means to ends; e.g., when a bird builds its nest. Answer. This is true; but the design is not in the animal, but in Him who made the animal such that it must act in that manner, i.e., in the Creator; just as the intelligence that guides the hands of a watch is not in the watch, but in its maker.
2. The watch does not perceive, while the brute does; there is no parity. Answer. There are many cases in which the brute acts for a remote end of which it has no more knowledge at the time of its action than the machine has of the purposes of its maker; as when the bird builds a nest for its future offspring, the bee stores up honey in summer for its support in winter. The intelligence thus displayed is certainly not in the brute animal.
3. But the brute displays intelligence in directing means to proximate ends which it presently apprehends, as when it eats to satisfy its hunger and prolong its life. Answer. The future prolongation of life is not intended by brutes; they merely apprehend by sense the sensible good of food to satisfy their sensible appetite. The brute apprehends things in the concrete; there is no abstraction, and therefore no reasoning.
4. If a dog is called by his master, he will run around by a gate or by a staircase, just as a rational man would do; here he displays reason as well as man does. Answer. We know from other sources that man has reason. Such actions as the dog performs can all be explained by the sense-perceptions and the phantasms of the brute, together with its appetites and instincts, which we shall explain further on (No. 149).
5. Some brutes can understand language; they must therefore have abstract ideas. Answer. They merely associate certain familiar sounds with familiar phantasms. The parrot can even be taught to utter articulate sounds associated with his sensible appetites.
6. Darwin shows that some brute animals have improved themselves; for instance, that the dog has six different barks to express six different feelings. Answer. Darwin dues not prove that dogs have not always possessed the same accomplishment, but have invented it; if dogs may always have used the same barks, their progress is not proved.
7. Some brutes learn to avoid traps, and one rat, for instance, will avoid them more skillfully than others. Answer. The association of phantasms suffices to produce this skill; and one rat may have acquired more of such experience than another. Besides, animals of the same species may have a more or less perfect organism, and, therefore, more skill in animal actions.
149. While brute animals have not the faculty of reason, they have a power or aptitude for the proper guidance of their actions which supplies for them the place of reason; it is called instinct. It may be defined as the natural impulse that prompts animals to do what is useful to the individual and to the species. It is not something superadded to the animal, but it is the sensitive tendency of its sensitive nature -- for instance, its inclination to eat when hungry, to rest when fatigued, etc.
150. Intinct prompts animals, not only to embrace what they sensibly apprehend as present good, and to shun what they apprehend as present evil for themselves; but also to do those preparatory actions which are naturally and sensibly connected with the gratification of animal appetites, such as looking for food, retiring to their lair, and even excavating a hole, spinning a web, storing up food, building a nest, etc.
151. In all instinctive actions there is an adaptation of means to ends, proximate and remote. The brute animal organically apprehends the nearer sensible ends, and such connection between means and ends as can be represented by phantasms; for instance, it perceives the sensible satisfaction of eating and resting, and the material relations between itself and its food and lair; but it does not apprehend the more remote ends, such as the future prolongation of life, the future propagation of its species, etc. The entire adaptation of means to ends, manifested in the workings of animal instinct, is the work of the Creator, who made the nature, the powers, and the tendencies of animals such as we find them at present.
152. We can the more easily understand the workings of instinct, because we experience them in ourselves. In brutes, however, they are far more perfect than in man, for they are intended by the Creator to be the sole guides of their actions. In man they are to be supplemented by the nobler faculty of reason, to which instinct is intended to be subservient. On many occasions we have nothing but instinct to guide us, as in early infancy and in many animal functions throughout life, such as breathing, swallowing, sleeping, closing our eyelids at the approach of danger, withdrawing our tongue before the closing teeth, etc. ln all such adaptations of means to ends we know that reason has usually no part. On many other occasions we are conscious that we are drawn one way by our sensible appetites and another way by our reason; the latter ought then to be obeyed.
153. Thesis VII. Plants and brute animals are intended for the use of man.
Proof 1. The purpose for which an object is intended, especially when it is of a complicated and delicately adapted structure, can be known by examining its fitness to accomplish a certain end or purpose; else we should have to grant that the striking adaptation of means to ends is an effect without a proportionate cause. Now, plants and animals are most delicate contrivances of intricate structure, and they are admirably adapted to the use of man. Therefore they are made for it.
Proof 2. All things are created for the extrinsic glory of God (Nos. 113 to 115); now, irrational things cannot by themselves glorify God, but only through man, being in some way of use to man; hence they are intended for the use of man.
154. Irrational creatures may be of use to man, and thus glorify God through man, in various ways: 1. By displaying to the eyes of man the power, wisdom, goodness of their Maker, and thus prompting man to love and praise God. 2. By supplying the bodily wants of man, and thus aiding him to serve God. 3. By administering aids to his rational pleasures, thus inducing him to love his God, and to serve him cheerfully. 4. Even things which molest man, such as the inclemencies of the seasons, beasts of prey, troublesome insects, etc., render service to man, making him more industrious, cleanly, provident, etc., and enabling him to bear the ills of life in the spirit of dutiful submission to the sovereign will of God.
155. Objections: 1. Many creatures are absolutely useless or even injurious to man. Answer. There are creatures of which we do not know the use; but it does not follow that they are of no use. From the fact that the vast majority of creatures are known to be very useful, we should rather conclude by induction that the others also answer a useful purpose.
2. Some plants and animils are known to be injurious. Answer. They may be injurious in some respects, and yet be very beneficial in other respects; thus, poisons become medicines in the hands of science.
156. Thesis VIII The species of plants and animals are ftxed -- i.e., incapable of transformation.
Explanation. By a species we mean a class of plants or animals which have characteristic properties in common and can be indefinitely propagated without changing those characteristics. A species may indeed produce a variety -- i.e., one or more individual plants or animals marked by some striking peculiarity not common to the species generally. A race is a variety perpetuated through several generations. Thus, in the canine species, we have many races that differ considerably from one another; still, all have certain characteristics in common, which mark them as belonging to the canine species. By saying that the species of plants and animals are fixed, we do not mean that no new races may arise and be propagated; but we here assert that the changes will never result in the evolution of new species. The crucial test, by which the distinction of species is known, is this: if animals can be paired together and thus propagate an indefinitely fertile offspring, they are of the same species; else they are not. Thus horses and asses are known to be different species, because, although they can by crossing generate the mule, still this hybrid is incapable of continued propagation. It is also important to notice that those scientists who maintain the evolution or transformation of species as a theory pretend that the new organisms evolved are usually more perfect than the antecedent species.
Proof 1. There can be no effect without a proportionate cause; but if higher species were evolved from lower, the improved new species would be without a proportionate cause. For inasmuch as the new species is more perfect than the old, it has no cause in the old. The new offspring of plants and animals may, at the most, have some accidental superiority over the parent stock, being born and raised under more favorable circumstances, but accidental changes constitute no specific difference.
Proof 2. By induction. Though scientists have now been at work for many years in exploring lands and seas, in examining the fossil remains of countless species of plants and animals, and in applying all the inventive genius of man to obtain and perpetuate new varieties and races, they have never yet been able to exhibit a single decisive proof that a transformation of species has ever taken place. Animals are now as they are represented on the pyramids or found mummified in the tombs of Egypt, as they were before they left their fossil forms in the rocks. Many species have become extinct, others are found now of which no very ancient specimens have been discovered; but it cannot be proved that any species was ever evolved from any other.
Proof 3. That the test of indefinitely continued fertility in the species is the crucial test by which the theory of evolution must be judged, and that the theory cannot stand this test, is acknowledged by its ablest advocates. "Without verification," says Tyndall, "a theoretic conception is a mere figment of the intellect" (Fragments of Science, p. 469). "Our acceptance of the Darwinian hypothesis," says Huxley, "must be provisional as long as one link in the chain of evidence is wanting; and as long as all the animals and plants certainly produced by selective breeding from a common stock are fertile, and their progeny are fertile with one another, one link will be wanting" (Man's Place in Nature, p. 107). Therefore, the theory which contradicts our thesis is a mere figment of the intellect. (See No. 209.)
157. Objections: 1. Paleontology shows that the fossils found in the higher strata of the earth belong to more perfect species of plants and animals than those in the lower strata; there must have been an evolution of less perfect into more perfect species. Answer. The fact stated is not found to be true in all cases; but even if true, it would only show that there is order in the works of the Creator, not that the higher species are evolved from the lower. Post hoc, ergo propter hoc, is a sophism.
2. Anatomy proves that all the forms of life are constructed according to a uniform type or plan, so as to constitute a regular system. Answer. This, too, shows that there is symmetry in the works of God, but not that there is evolution of species in nature; you might as well say that all Gothic buildings are evolved from one another.
3. Anatomy also reveals the fact that the more perfect animals retain certain rudimentary organs which are of no present use, and which are mere remnants of a former useful structure; therefore evolution has taken place. Answer. Anatomy does not prove that the so-called rudimentary structures are of no use to those higher animals; they serve, at least, for ornament, and give symmetry to the creation. Darwin classes our sense of smell and our external ear among these useless remnants, while it is certain that they are very useful; such pleadings exhibit much weakness in the theory.
4. Geography shows that certain species of plants and animals are peculiar to certain climates; therefore the influence of the climate must have produced them. Answer. The wisdom of God has provided for each climate its appropriate fauna and flora, usually by the natural process of variety of races, never by the evolution of new species.
5. Physiology has discovered that the embryo of a higher animal species passes through the forms of all the lower species in its process of evolution. Answer. The development of an individual animal is one thing, and that of species from species is quite another; the one fact does not prove the other. Besides, the statement itself is inexact, and the order of embryonic evolutions is different in different species.
6. A worm becomes a butterfly; therefore a less perfect animal may be developed into one more perfect. Answer. Only those worms become butterflies which come from the eggs of butterflies; the species remains unchanged.
7. Even the Schoolmen admitted the possibility of spontaneous generation -- i.e., of the generation of an animal from brute matter only, without a living germ. Answer. They admitted it as possible in connection with a higher influence proceeding from a heavenly body, but not as resulting from the combination of merely material elements; this higher influence might, in their opinion, replace the living germ, thus showing that they felt convinced that life cannot proceed from lower elements only, no matter how combined. (Pesch, Inst. Phil. Nat., No. 190.)
158. It may be asked whether the Creator could have established a series of evolutions from less perfect to more perfect species.
Reason answers that God can do all that is not self-contradictory. Now, such a series, taken in one sense, would be self-contradictory, but not in another sense. It is absurd that a superior effect should proceed entirely from an inferior cause, but not that God should supply by His own action whatever perfection is added to the effect -- i.e., to the new generation. Nor is it evidently impossible that the Creator should direct the evolution of a lower into a higher species by the agency of second causes, wisely combined for that purpose. But it is metaphysically impossible that a merely fortuitous combination of causes, without a wise designer to direct the work, should build up a most wonderful system of development, running through the whole vegetable and animal kingdoms, such as scientists claim that evolution has accomplished. To say that merely blind forces produce so much beauty and harmony, is fully as absurd as to pretend that a man can compose a grand and harmonious poem without knowing a word of the language in which it is written. A system that ascribes effects to totally inadequate causes is unscientific.