Letter to Fromondus

LETTRE 8. Version.

It seems to me that it is not without reason that Mr. Fromondus recalled, in the Exordium of the Objections he has made against me, the Fable of Ixion, not only because he wisely warns me to be cautious of embracing vain and deceptive opinions instead of the truth (which I will strive to do to the best of my ability, and which I have always endeavored to do until now), but also because he himself, when he believes he is challenging my Philosophy, refutes nothing other than that hollow and subtle Philosophy, composed of Void and Atoms, (which is customarily attributed to Democritus and Epicurus) or others like it, which do not concern me at all.

As a first point, when on pages 46 and 47 of the Method, it states that such noble Actions as Vision, and several other similar ones, cannot arise from a cause as vile and crude as natural heat; it assumes Clerselier II, 36 that I believe animals see everything just as we do, that is to say, by sensing or thinking that they see; this opinion is thought to have been that of Epicurus; and today it is almost universally accepted and approved by everyone.

And yet, throughout this entire part, up to page 60, I demonstrate quite clearly that my opinion is not that animals see as we do, when we are aware that we see; but rather that they see as we do, when our mind is diverted and strongly focused elsewhere. Even though, at such times, the images of external objects are projected onto the retina, and perhaps also that their impressions made on the optical nerves cause our limbs to move in various ways, we nonetheless do not perceive any of this; in which case we do not move in any way different from automata, for whom no one would claim that natural heat is insufficient to provoke all the movements that occur within them.

2. When on page 56. he asks what need there is of putting substantial souls into brute beasts, and says that by this we may perhaps give the atheists an opportunity to exclude the rational soul from the human horn. This concerns no one less than me, who firmly believes in the Holy Scriptures, and who has explained clearly enough, if I am not mistaken, that the Soul of brutes is nothing else than their blood, to be known, he who, being heated in their hearts, and converted into spirits, spreads from the arteries through the brain to all the nerves, and in all the muscles.

From which doctrine it results that there is such a great difference between the souls of beasts and ours, that I do not know if anyone has ever invented a stronger argument and a more powerful reason to convince and confuse atheists, and to persuade that the human spirit is not drawn from the power of matter. But for those who attribute to animals, I do not know what substantial souls, different from blood, heat, and spirits, I find them quite hindered: For, first of all, I do not see what they have to respond to chapter 17, Clerselier II, 37 of Leviticus, verse 14, where it is expressly stated.

For the soul of all flesh is in the blood; and you shall not eat the blood of any flesh, for the soul of the flesh is in the blood. As also in chapter 12 of Deuteronomy, verse 23. Above all, take care not to eat blood, for they have the blood for soul, and for this reason you must not eat the soul with the flesh. There are other similar passages, which seem to me much clearer than those brought against certain other opinions that are condemned by some, simply because they appear contrary to holy Scripture.

Moreover, I do not understand how, after having established so little difference between the operations of man and those of the beast, one can be persuaded that there is such a great disparity between the nature of the Rational Soul and that of the Sensitive Soul, such that the Sensitive Soul, when alone, is of a Corporeal and mortal nature, and that when joined to the Rational Soul, it becomes of a spiritual and immortal nature.

For, in what do you think, I beseech you, that they believe that Sense is distinct from Reason? It is to be understood that the knowledge of sense is apprehensive and simple, and therefore in no way subject to falsehood or error, while the knowledge of reason is somewhat more complex, and can be made through the forms and convolutions of syllogisms; which does not seem to demonstrate that it is more perfect; especially since they assert that the knowledge of God and the Angels is simple and intuitive, or only apprehensive, and that it is not attached to any form of reasoning. Thus, according to their account, the sense of beasts, (if it is permissible to speak in such terms) will be closer to the knowledge of God and the Angels than human reasoning.

I could have added this and several other similar things, not only to what I have written about the Soul of man, but almost to all the other matters I have addressed, in order to strengthen my propositions; however, I have deliberately omitted all of this, in order not to teach Clerselier anything false while attempting to refute others, and also in order not to openly insult any of the opinions that are accepted in the Schools.

3. When on page 50, he states that there should not be less heat in the heart than in a furnace, so that the drops of blood may be rarefied quickly enough to expand. He seems not to have taken notice of how milk, oil, and almost all other liquids, when placed over the fire, gradually and very slowly expand at first; but when they reach a certain degree of heat, they swell suddenly, almost in an instant; so that if one does not remove them from the fire immediately, or at least uncover the vessel they are in, so that the Spirits, which are the main cause of this rarefaction, may escape, a good portion will flee and spill into the ashes.

And this degree of heat must be varied, according to the nature of the liquid, because there are even some that are barely warm, which rarefy and expand in such a way: For if this had been observed, one would have easily judged that the blood contained in the veins of each animal closely approaches the degree of heat that it must acquire in the heart, in order to be rarefied almost instantaneously.

4. He proves that he has embraced the clouds of the Philosophy of Democritus, instead of mine, in his comment about page 4 of Dioptrique.

He denies that I have explained well how a Luminous Ray transmits its rays in an instant, by the Comparison of a Blind Man’s stick.

He says that the ray that comes out of the Sun’s body should rather be compared to an arrow that comes out of a bow, and that crosses the air successively, and not in an instant, etc.

Does he not take Leucippus, or Epicurus, or like I believe Lucretius, who, if I am not mistaken, spoke somewhere in his verses, Of the Darts of the Sun, for me here?

For me, not supposing any Void at all, but having expressly said the contrary to Clerselier II, 39, that all the Spaces from the Sun to us are full of some substance, indeed very fluid, but also therefore all the more continuous, which I have called Subtle Matter.

I have explained how the rays of light are transmitted in an instant through my analogies of:

• the stick, and
• the vat full of crushed grapes

He says that my Philosophy is a bit crude and coarse because I believe that there are substances that can easily penetrate the pores of glass.

But I think the coarser and less solid Philosophy it the one which maintains that there are no pores in glass because sound cannot pass through there.

In reality, sound cannot pass through glass because it relies on air which needs pores that are large and wide enough.

5. He says that if Light is only transferred by certain Substances moved Locally, then any movement of these Substances is Light.

But this means that since iron does not become red and glowing unless it is hot, then every time it is hot in some way, it will also be in some way red and glowing.

I admit that any impulse of the subtle matter that has reached a certain degree of speed causes the sensation of Light.

Thus, when one is struck in the eyes, or when one rubs them a bit too hard, it is customary for certain sparks to appear to us, even though no rays of light are otherwise coming towards them.

But I deny that a slower and more ordinary movement of this Substance can cause light, just as moderate heat is not sufficient to make iron red.

6. What he says on page 17 will be clear if he pays attention to page 18.

The ball pushed from A to B must at the same instant reach:

• some point on the circumference of the Circle DI and
• some point on the straight line FEI

This is because there is only the single point I, at least below the canvas, where the straight line ``FEIintersects the CircleDI. And so, it clearly appears that the ball must then go towards Iand not towardsD`.

7. I have said that air impedes the passage of light more than water does, and the experience of diving will not pose any obstacle to him if he distinguishes between the multitude of rays and the ease with which each ray individually can penetrate such or such a Diaphanous Substance.

I agree that air admits many more rays into itself than water does, from the surface of which many are reflected, and which, as clear as it may be, still has several earthly particles interspersed among them, which, encountering the rays that have penetrated it and sometimes opposing some, sometimes others, easily cause them all to reflect before they have penetrated deeply.

But this does not prevent the same ray that passes through air and water from passing more easily through the latter than the former, which is all I have said, and which I believe I have also demonstrated, if I understand what a demonstration is.

8. Ce qu’il dit sur la page 50. manquer touchant la cause Clerselier II, 41 de la diversité des couleurs, il le trouvera à la fin de la unziéme page, et au commencement de la 40. expliqué comme ie croy suffisamment ; et de plus demonstré plus bas si amplement, depuis la page 254. iusques à la page 261. que ie n’estime pas qu’il soit necessaire de rien adjoûter icy davantage.