Now if after that one reviews all the demonstrations or corollaries of the letter, one will be able to admit or reject the majority of its assertions, in accordance with the interpretation one may make of them.  If by ‘reality’ one means only perfections or positive realities, God is the only true cause; but if that which involves limitations is included under the realities, one will deny a considerable portion of the theses, and the author himself will have shown us the example.  It is in order to render the matter more comprehensible that I used in the Essays the example of a laden boat, which, the more laden it is, is the more slowly carried along by the stream.  There one sees clearly that the stream is the cause of what is positive in this motion, of the perfection, the force, the speed of the boat, but that the load is the cause of the restriction of this force, and that it brings about the retardation.

It is praiseworthy in anyone to attempt to apply the geometrical method to metaphysical matters.  But it must be admitted that hitherto success has seldom been attained:  and M. Descartes himself, with all that very great skill which one cannot deny in him, never perhaps had less success than when he essayed to do this in one of his answers to objections.  For in mathematics it is easier to succeed, because numbers, figures and calculations make good the defects concealed in words; but in metaphysics, where one is deprived of this aid (at least in ordinary [391] argumentation), the strictness employed in the form of the argument and in the exact definitions of the terms must needs supply this lack.  But in neither argument nor definition is that strictness here to be seen.

The author of the letter, who undoubtedly displays much ardour and penetration, sometimes goes a little too far, as when he claims to prove that there is as much reality and force in rest as in motion, according to the fifth corollary of the second proposition.  He asserts that the will of God is no less positive in rest than in motion, and that it is not less invincible.  Be it so, but does it follow that there is as much reality and force in each of the two?  I do not see this conclusion, and with the same argument one would prove that there is as much force in a strong motion as in a weak motion.  God in willing rest wills that the body be at the place A, where it was immediately before, and for that it suffices that there be no reason to prompt God to the change.  But when God wills that afterwards the body be at the place B, there must needs be a new reason, of such a kind as to determine God to will that it be in B and not in C or in any other place, and that it be there more or less promptly.  It is upon these reasons, the volitions of God, that we must assess the force and the reality existent in things.  The author speaks much of the will of God, but he does not speak much in this letter of the reasons which prompt God to will, and upon which all depends.  And these reasons are taken from the objects.