The Nerves and the Refilling of a Vacuum

Erasistratus writes about nutrition in book 2 of his “General Principles.”

He believes that matter tends to fill a vacuum. But he only believed it for the veins and their contained blood.211

When blood is running through the veins, an absolutely empty space cannot result.

The veins cannot collapse because the adjoining quantum of fluid flows in and fills the place of the fluid evacuated.

The veins are nourished this way.

• They get the benefit of the blood which they contain.

The nerves do not contain blood.

He says that a nerve has within itself veins and arteries, like a rope woven by Nature out of 3 different strands.

If the nerve contains within itself a blood-vessel it will no longer need the adventitious flow of other blood from the real vein lying adjacent; this fictitious vessel, perceptible only in theory,214 will suffice it for nourishment.

This small vessel will nourish itself.

But it will not be able to nourish this adjacent simple nerve or artery, unless these have some innate proclivity for attracting nutriment.

How could the simple nerve attract its nourishment like the composite veins?

According to Erasistratus, a nerve has a cavity that is not occupied with blood, but with psychic pneuma

The nutriment is introduced, not into this cavity, but into the nerve-vessel containing it. This creates nourishment and growthh.

This simple nerve is so small.

If you prick it at any part with the finest needle you will tear the whole three of them at once.

It cannot have empty space inside it.

And an emptied space which merely existed in theory could not compel the adjacent fluid to come and fill it.

Is this small elementary nerve one and continuous?

Or does it consist of many small bodies, such as those assumed by Epicurus, Leucippus, and Democritus?

The Erasistrateans are at variance on this subject.

1. Some think that it is one and continuous since it is simple.

In this case, what is evacuated from it in the so-called insensible transpiration of the physicians will leave no empty space in it.

Otherwise it would not be one body but many, separated by empty spaces.

2. Some think that it is made up of yet other elementary bodies.*

Superphysics Note

They are both correct

In this case, we have “escaped by the back door” according to Asclepiades. This is because this postulates inharmonious elements.

This makes Nature “inartistic”.

This is why I think that some of the Erasistrateans have very foolishly reduced the simple vessels to elements such as these.

Yet it does not matter because Erasistratus’s theory of nutrition is absurd.

They believe that the large perceptible nerves are made up of these minute simple vessels.

But it is impossible for any “refilling of a vacuum” if the nerves are simple and continuous.

• This is because no vacuum can occur in a continuum even if anything does run away.*

Superphysics Note

Galen is unable to understand that immaterial energy can create nourishment

This is because the parts left come together (as is seen in the case of water) and again become one, taking up the whole space of that which previously separated them.

“Refilling” is also impossible if the nerves are made up of small bodies since none of their elements need it.

This is because the refilling principle only holds for perceptible things, and not for theoretical ones.

Erasistratus acknowledges this.

He says that his nerves are not such a vacuum interspersed in small portions among the corpuscles.

Instead, this vacuum is clear, perceptible, complete in itself, large in size, and evident.

He writes: “there cannot be a perceptible space which is entirely empty”

Those Erasistrateans who reduce the vessel called primary and simple into other elementary bodies should give up their opinion because they are also at variance with Erasistratus in this matter.

Their hypothesis could not escape the difficulty regarding nutrition. It is not even in consonance with the view of Erasistratus.

For, if we do not grant a certain unity of substance218 to these simple structures as well, and if we arrive eventually at inharmonious and indivisible elements,219 we shall most assuredly deprive Nature of her artistic skill, as do all the physicians and philosophers who start from this hypothesis.

For, according to such a hypothesis, Nature does not precede, but is secondary to the parts of the animal.220 Now, it is not the province of what comes secondarily, but of what pre-exists, to shape and to construct.

Thus we must necessarily suppose that the faculties of Nature, by which she shapes the animal, and makes it grow and receive nourishment, are present from the seed onwards; whereas none of these inharmonious and non-partite corpuscles contains within itself any formative, incremental,221 nutritive, or, in a word, any artistic power; it is, by hypothesis, unimpressionable and untransformable,222 whereas, as we have previously shown,223 none of the processes mentioned takes place without transformation, alteration, and complete intermixture.

And, owing to this necessity, those who belong to these sects are unable to follow out the consequences of their supposed elements, and they are all therefore forced to declare Nature devoid of art. It is not from us, however, that the Erasistrateans should have learnt this, but from those very philosophers who lay most stress on a preliminary investigation into the elements of all existing things.

Now, one can hardly be right in supposing that Erasistratus could reach such a pitch of foolishness as to be incapable of recognizing the logical consequences of this theory, and that, while assuming Nature to be artistically creative, he would at the same time break up substance into insensible, inharmonious, and untransformable elements. If, however, he will grant that there occurs in the elements a process of alteration and transformation, and that there exists in them unity and continuity, then that simple vessel of his (as he himself names it) will turn out to be single and uncompounded. And the simple vein will receive nourishment from itself, and the nerve and artery from the vein.

How, and in what way? For, when we were at this point before, we drew attention to the disagreement among the Erasistrateans,224 and we showed that the nutrition of these simple vessels was impracticable according to the teachings of both parties, although we did not hesitate to adjudicate in their quarrel and to do Erasistratus the honour of placing him in the better sect.225

I follow the doctrine which assumes this elementary nerve is a single, simple, and unified structure.

and let us consider how it is to be nourished; for what is discovered here will at once be found to be common also to the school of Hippocrates.

It seems to me that our enquiry can be most rigorously pursued in subjects who are suffering from illness and have become very emaciated, since in these people all parts of the body are obviously atrophied and thin, and in need of additional substance and feeding-up; for the same reason the ordinary perceptible nerve, regarding which we originally began this discussion, has become thin, and requires nourishment.

Now, this contains within itself various parts, namely, a great many of these primary, invisible, minute nerves, a few simple arteries, and similarly also veins.

Thus, all its elementary nerves have themselves also obviously become emaciated; for, if they had not, neither would the nerve as a whole; and of course, in such a case, the whole nerve cannot require nourishment without each of these requiring it too.

Now, if on the one hand they stand in need of feeding-up, and if on the other the principle of the refilling of a vacuum227 can give them no help—both by reason of the difficulties previously mentioned and the actual thinness, as I shall show—we must then seek another cause for nutrition.

How is it, then, that the tendency of a vacuum to become refilled is unable to afford nourishment to one in such a condition?

Because its rule is that only so much of the contiguous matter should succeed as has flowed away.

This is sufficient for nourishment in the case of those who are in good condition, for, in them, what is presented228 must be equal to what has flowed away. But in the case of those who are very emaciated and who need a great restoration of nutrition, unless what was presented were many times greater than what has been emptied out, they would never be able to regain their original habit.

It is clear, therefore, that these parts will have to exert a greater amount of attraction, in so far as their requirements are greater. And I fail to understand how Erasistratus does not perceive that here again he is putting the cart before the horse.

Because, in the case of the sick, there must be a large amount of presentation228 in order to feed them up, he argues that the factor of “refilling”227 must play an equally large part.

How could much presentation take place if it were not preceded by an abundant delivery229 of nutriment?

If he calls the conveyance of food through the veins delivery, and its assumption by each of these simple and visible nerves and arteries not delivery but distribution,230 as some people have thought fit to name it, and then ascribes conveyance through the veins to the principle of vacuum-refilling alone, let him explain to us the assumption of food by the hypothetical elements.231

There is no such thing as the refilling of a vacuum especially where the parts are very attenuated.

Erasistratus writes about these cases in Book 2 of his “General Principles”:

I accept the words “through the sides.”

This is because if the simple nerve took in food through its mouth it would not be able to distribute it through its whole substance simce its mouth is dedicated to the psychic pneuma.232

It can, however, take it in through its sides from the adjacent simple vein.

I accept this.

I agree that it is attracted. But this is not through the tendency of evacuated matter to be replaced.