The Remaining Works of Benedictus de Spinoza

But this whole unity of subject and object is not necessarily such, except when the subject is thinking. Furthermore, every deduction of derived things or special reasons from one principle or absolute and inherently true reason does not occur except in the realm, so to speak, of reason or formal truth. Finally, that necessary identification of diverse things, without which there would be neither affirmation nor negation, likewise pertains to the form of thinking. But whether two objects that exist in the mind and are held by a given thinker at this moment as one in a certain respect—that is, conceived under the form of unity—are one by their own nature (which we are forced to attribute to those things we cannot help but think of with the notion of existence), or whether they only seem to be one to the thinker at this moment, that thinker certainly cannot formally judge and decide, however much he may be a subject-object—that is, even if he thinks from his own subjective unity with the object. This, of course, depends on the matter, as everyone either shouts or senses. But the matter (I refer to the internal matter of thinking) does not depend on that mode by which it is now thought of by this or that person, that is, reduced from diversity to unity. Rather, the ideal object—that is, that which is in the mind and because of which the mind can be rightly called a subject-object—whenever it is presented to the mind to be thought of with existence, is subject to necessity or the reality of its own nature, indeed in such a way that the ideal object is identified with another formally in vain and erroneously, unless it must be identified by the reality of its nature.