The Animal Spirits

The animal spirits are like a very subtle wind, or a very pure and vivid flame.

• It continually rises in great abundance from the heart to the brain.

From the brain, it penetrates through the nerves into the muscles, and moves all the parts.

This is why the most agitated and penetrating blood are the fittest to compose these spirits going towards the brain,

The rules of mechanics are the same with those of nature.

When many objects tend at once to the same point where there is insufficient room for all, the weaker and less agitated parts are driven aside from that point by the stronger.. An example is the blood flowing to the brain from the left cavity of the heart.

My Treatise explains the following:

• The fabric of the nerves and muscles gives the animal spirits contained in it the power to move the members. This is seen in the heads of people that have been decapitated still able to move and bite the earth, although no longer animated.
• What changes must take place in the brain to produce waking, sleep, and dreams?
• How do light, sounds, odours, tastes, heat, and all the other qualities of external objects impress it with different ideas through the senses?
• How does hunger, thirst, and the other internal affections can likewise impress upon it diverse ideas?
• What is the common sense (sensus communis) that receives these ideas?
• What is the memory which retains them?
• What is the imagination which can change them in various ways, and out of them compose new ideas?
• How can the imagination distribute the animal spirits through the muscles and cause the body to move?

Nor will this appear at all strange to those who are acquainted with the variety of movements performed by the different automata, or moving machines fabricated by human industry, and that with help of but few pieces compared with the great multitude of bones, muscles, nerves, arteries, veins, and other parts that are found in the body of each animal. Such persons will look upon this body as a machine made by the hands of God, which is incomparably better arranged, and adequate to movements more admirable than is any machine of human invention.

Were there such machines exactly resembling organs and outward form an ape or any other irrational animal, we could have no means of knowing that they were in any respect of a different nature from these animals;

But if there were machines bearing the image of our bodies, and capable of imitating our actions as far as it is morally possible, there would still remain two most certain tests whereby to know that they were not therefore really men.

Of these the first is that they could never use words or other signs arranged in such a manner as is competent to us in order to declare our thoughts to others= for we may easily conceive a machine to be so constructed that it emits vocables, and even that it emits some correspondent to the action upon it of external objects which cause a change in its organs;

For example, if touched in a particular place it may demand what we wish to say to it; if in another it may cry out that it is hurt, and such like; but not that it should arrange them variously so as appositely to reply to what is said in its presence, as men of the lowest grade of intellect can do.

The second test is, that although such machines might execute many things with equal or perhaps greater perfection than any of us, they would, without doubt, fail in certain others from which it could be discovered that they did not act from knowledge, but solely from the disposition of their organs= for while reason is an universal instrument that is alike available on every occasion, these organs, on the contrary, need a particular arrangement for each particular action; whence it must be morally impossible that there should exist in any machine a diversity of organs sufficient to enable it to act in all the occurrences of life, in the way in which our reason enables us to act.

These two tests can let us know the difference between men and brutes.

All men, even idiots, can join together different words to make their thoughts understood.

• On the other hand, no animals can do the same.

This inability does not arise from lack of organs. Magpies and parrots can utter words like ourselves. But they are unable to speak as we do and show that they understand what they say.

This proves that animals have less reason than man, but that they have none at all. Very little is required for a person to speak.

The soul of brutes are of a nature totally different from ours because:

• a certain inequality of capacity is observable among animals of the same species, as well as among men
• some are more capable of being instructed than others

If they were the same then the most perfect ape or parrot should be equal to the most stupid human infant.

We should not confound speech with the natural movements which indicate the passions, and can be imitated by machines as well as manifested by animals; nor must it be thought with certain of the ancients, that the brutes speak, although we do not understand their language.

For if such were the case, since they are endowed with many organs analogous to ours, they could as easily communicate their thoughts to us as to their fellows.

There are many animals which are more hardworking than us in certain actions.

The same animals are yet observed to show none at all in many others= so that the circumstance that they do better than we does not prove that they are endowed with mind, for it would thence follow that they possessed greater reason than any of us, and could surpass us in all things; on the contrary, it rather proves that they are destitute of reason, and that it is nature which acts in them according to the disposition of their organs= thus it is seen, that a clock composed only of wheels and weights can number the hours and measure time more exactly than we with all our skin.

The reasonable soul:

• is not educed from the power of matter. Instead, the soul must be expressly created.
• is not sufficient for it to be lodged in the human body exactly like a pilot in a ship, unless perhaps to move its members, but that it is necessary for it to be joined and united more closely to the body, in order to have sensations and appetites similar to ours, and thus constitute a real man.

The subject of the soul is of the greatest moment.

Some people make the mistake of denying God’s existence.

There is an idea that the soul of brutes is of the same nature with our own. This idea leads feeble minds astray from the straight path of virtue the most.

This makes them think that there is nothing after this life just like flies and ants have nothing to hope or fear for.

Instead, we should think that the reason of animals are different. The soul is wholly independent of the body. It cannot die with the body. Therefore, it is immortal because nothing can destroy it.