80. Kant observes that the _nervus probandi_ of the argument is in the fact that many representations cannot form a thought, except inasmuch as they are contained in the absolute unity of the thinking subject; "but no one," he says, "can prove this proposition _by conceptions_. Where could he begin? The proposition: 'A thought can only be the effect of the absolute unity of the thinking subject,' cannot be analyzed; the unity of thought (and even thought results from many representations) is collective; and as to simple conceptions, their unity may just as well be referred to the collective unity of substances which contribute to produce the thought (just as the motion of a body is the motion of all its parts) as to the absolute unity of the subject. The necessity of the supposition of a simple substance cannot consequently be known by the rule of identity in a composite thought. No one who understands the reason of the possibility of synthetic judgments _a priori_, as we have explained them above, will dare to affirm that this proposition can be known synthetically, and perfectly _a priori_, or by pure conceptions." This reasoning is pure sophistry, and will vanish in the light of evidence. 81. In the first place, it is not correct to say that all thoughts result from many representations; in the perception of a simple idea, as of being, for example, there are not many representations; therefore Kant's argument fails at the first step; for if there be even one thought which requires simplicity, it has already been demonstrated that, if the soul is simple in one instance it cannot cease to be so in another. 82. Let us now examine how the diversity of representations enter into those thoughts which admit of this diversity. When these representations form what is called a thought, they are united, as it were, in a point which requires the unity of the perception and of the subject perceiving. In the thought called judgment various representations are combined, that of the subject and that of the object; but these different representations do not constitute the thought called judgment, except inasmuch as they are presented as connected with the relation which authorizes us to affirm or deny the predicate of the subject; therefore at the bottom of the diversity there is unity, that is to say, the relation; therefore the thought by which this relation is perceived is one, and the action of perceiving is essentially one, notwithstanding the variety of the representations.