’VII.  The thing would be less incomprehensible if it were supposed that the soul of man is not one spirit but rather a multitude of spirits, each of which has its functions, that begin and end precisely as the changes made in a human body require.  By virtue of this supposition it should be said that something analogous to a great number of wheels and springs, or of matters that ferment, disposed according to the changes of our machine, awakens or lulls asleep for a certain time the action of each of those spirits.  But then the soul of man would be no longer a single substance[44] but an ens per aggregationem, a collection and heap of substances just like all material beings.  We are here in quest of a single being, which produces in itself sometimes joy, sometimes pain, etc., and not of many beings, one of which produces hope, another despair, etc.

’In these observations I have merely cleared and unfolded those which M. Leibniz has done me the honour to examine:  and now I shall make some reflexions upon his answers.

’VIII.  He says (ibid., p. 332) that the law of the change which happens in the substance of the animal transports him from pleasure to pain at the very moment that a solution of continuity is made in his body; because the law of the indivisible substance of that animal is to represent what is done in his body as we experience it, and even to represent in some manner, and with respect to that body, whatever is done in the world.  These words are a very good explication of the grounds of this system; they are, as it were, the unfolding and key of it; but at the same time they are the very things at which the objections of those who take this system to be impossible are levelled.  The law M. Leibniz speaks of supposes a decree of God, and shows wherein this system agrees with that of occasional causes.  Those two systems agree in this point, that there are laws according to which the soul of man is to represent what is done in the body of man, as we experience it.  But they disagree as to the manner of executing those laws.  The Cartesians say that God executes them; M. Leibniz will have it, that the soul itself does it; which appears to me impossible, because the soul has not the necessary instruments for such an execution.  Now however infinite the power and knowledge of God be, he cannot perform with a machine deprived of a certain piece, what requires the concourse of such a piece.  He must supply that defect; but then the effect would be produced by him and not by the machine.  I shall show that the soul has not the instruments requisite for the divine law we speak of, and in order to do it I shall make use of a comparison.