TO A FRIEND OF MR DESCARTES

To be delivered to him. LETTER FIRST. SIR,

Not daring to address myself directly to Mr Descartes to propose my difficulties to him, I borrow your credit, to beg you to present them to him, and to try to arrange that he takes them in good part, as coming from a person who has more desire to learn than to contradict.

Firstly, the second rule of his moral philosophy seems to be dangerous, since it states that one must hold to the opinions that one has once decided to follow, even if they were the most doubtful, just as if they were the most assured: for if they are false or evil, the more one follows them, the more one will become entangled in error or in vice.

2. The third rule is rather a fiction for flattering and deceiving oneself, than a resolution befitting a Philosopher, who ought to despise possible things, if it is expedient for him, without feigning them impossible: and a man of common sense will never persuade himself that nothing is in his power except his thoughts.

3. The first principle of his philosophy is, I think, therefore, I am. It is no more certain than many others, such as this one: I breathe, therefore I am; or this other: every action presupposes existence. To say that one cannot breathe without a body, but that one can think without it, is what would need to be shown by a clear demonstration: for although one can imagine that one has no body (though that is difficult enough), and that one lives without breathing; it does not follow that this is so in reality, and that one can live without breathing.

4. It would therefore be necessary to prove that the soul can think without the body; Aristotle indeed presupposes this in one of his axioms, but he does not prove it; he wants the soul to be able to act without organs; from which he concludes that it can exist without them, but he does not prove the first point, which is contradicted by experience: for one sees that those whose imagination is diseased do not think well; and if they had neither imagination nor memory, they would not think at all.

5. It does not follow from our doubting the things around us that there exists some being more perfect than ourselves. Most Philosophers have doubted many things, like the Pyrrhonians, and they did not from that conclude that there was a Divinity; there are other proofs for giving one the thought of it, and for proving it.

6. Experience shows that beasts make their affections and passions known by their kind of language, and that by many signs they show their anger, their fear, their love, their pain, their regret for having done wrong; witness what is read of certain horses that, having been employed to cover their mothers without knowing them, threw themselves down after having recognized them. It is true that one should not dwell on these stories; but it is evident that animals perform their operations by a principle more excellent than the necessity arising from the disposition of their organs; namely, by an instinct, which will never be found in a machine, or in a clock, which have neither passion nor affection, as animals do.

7. The Author says that the soul must necessarily be created, but it would have been good to give the reason for this.

8. If light were extended like a stick, it would not be a movement, but a pressing line; and if it were a movement made from the Sun to us, it would not be in an instant, seeing that every movement takes place in time; neither would it take place in a straight line, if it must pass, like the must from the vat, through an interval full of bodies larger than that subtle matter which carries it, and which can break the straight line by their agitation.

9. Since the Author professes to write methodically, clearly, and distinctly, it would seem fitting that he should show what this subtle matter is that he presupposes: for one asks with reason, firstly whether it exists, 2. whether it is elementary, or ethereal, and if being elementary, whether it is proper to, or common to, all the Elements.

10. If water is liquid only because this subtle matter makes it so, it will follow that ice will not melt sooner before the fire than elsewhere, or else one must admit that it is the fire, and not the subtle matter, that makes it liquid.

11. One finds it difficult to imagine that water has the shape of eels, and the reasons given for this on page 124 of the Book of Meteors, and explained in the Replies to Monsieur Fromont, conclude nothing other than that it must be slippery, and capable of accommodating itself to all sorts of figures, but one cannot conclude that it is in the form of eels; and if the most penetrating bodies must have such a figure, it will follow that air does so even more.

12. If salt makes itself tasted by its pointed and prickly figure, other bodies having the same figure will produce the same effect, even though they are insipid; it will also follow that liquids, which according to the Author have an eel-like and non-prickly figure, will not be tasted, especially those that are sweet and do not have the point of salt; finally, taste would be only an external figure, and not an internal quality; and the force that salt has to keep things from corrupting would consist only in its point and its figure.

13. If a body does not sink into water because it is equally thick at both ends, it will follow that all those of the same figure will not sink, and that those that have one end thicker will sink.

14. It would also follow that salt being of this figure, and like sticks that cannot bend, it would be easy to desalinate sea water by filtering it, or passing it through some body that has very narrow pores.

15. It is true that our French orthography has superfluities that need to be corrected, but this must be done without causing ambiguities: for one may doubt concerning the words cors and espris, whether the first might not mean horns, which we also call cors, and whether the other might not be taken for being enflamed with something. It is true that this is a Grammatical remark, and not a Philosophical one: that is why it has been placed outside the rank of the others, or perhaps it is the Printer’s fault.

I beg you to have the boldness I have taken in wishing my difficulties to be seen by a man of the merit of Monsieur Descartes kindly received; the little trouble that they will no doubt give him will make him more favorable to me, and you will oblige me to continue to be, as I have always been, SIR, Your most humble and most obedient servant, S. P.